bootstrap.bundle.js

   * @argument {Array} arr
   * @argument prop
   * @argument value
   * @returns index or -1
   */
  function find$1(arr, check) {
    // use native find if supported
    if (Array.prototype.find) {
      return arr.find(check);
    }

    // use `filter` to obtain the same behavior of `find`
    return arr.filter(check)[0];
  }

  /**
   * Return the index of the matching object
   * @method
   * @memberof Popper.Utils
   * @argument {Array} arr
   * @argument prop
   * @argument value
   * @returns index or -1
   */
  function findIndex(arr, prop, value) {
    // use native findIndex if supported
    if (Array.prototype.findIndex) {
      return arr.findIndex(function (cur) {
        return cur[prop] === value;
      });
    }

    // use `find` + `indexOf` if `findIndex` isn't supported
    var match = find$1(arr, function (obj) {
      return obj[prop] === value;
    });
    return arr.indexOf(match);
  }

  /**
   * Loop trough the list of modifiers and run them in order,
   * each of them will then edit the data object.
   * @method
   * @memberof Popper.Utils
   * @param {dataObject} data
   * @param {Array} modifiers
   * @param {String} ends - Optional modifier name used as stopper
   * @returns {dataObject}
   */
  function runModifiers(modifiers, data, ends) {
    var modifiersToRun = ends === undefined ? modifiers : modifiers.slice(0, findIndex(modifiers, 'name', ends));

    modifiersToRun.forEach(function (modifier) {
      if (modifier['function']) {
        // eslint-disable-line dot-notation
        console.warn('`modifier.function` is deprecated, use `modifier.fn`!');
      }
      var fn = modifier['function'] || modifier.fn; // eslint-disable-line dot-notation
      if (modifier.enabled && isFunction(fn)) {
        // Add properties to offsets to make them a complete clientRect object
        // we do this before each modifier to make sure the previous one doesn't
        // mess with these values
        data.offsets.popper = getClientRect(data.offsets.popper);
        data.offsets.reference = getClientRect(data.offsets.reference);

        data = fn(data, modifier);
      }
    });

    return data;
  }

  /**
   * Updates the position of the popper, computing the new offsets and applying
   * the new style.<br />
   * Prefer `scheduleUpdate` over `update` because of performance reasons.
   * @method
   * @memberof Popper
   */
  function update() {
    // if popper is destroyed, don't perform any further update
    if (this.state.isDestroyed) {
      return;
    }

    var data = {
      instance: this,
      styles: {},
      arrowStyles: {},
      attributes: {},
      flipped: false,
      offsets: {}
    };

    // compute reference element offsets
    data.offsets.reference = getReferenceOffsets(this.state, this.popper, this.reference, this.options.positionFixed);

    // compute auto placement, store placement inside the data object,
    // modifiers will be able to edit `placement` if needed
    // and refer to originalPlacement to know the original value
    data.placement = computeAutoPlacement(this.options.placement, data.offsets.reference, this.popper, this.reference, this.options.modifiers.flip.boundariesElement, this.options.modifiers.flip.padding);

    // store the computed placement inside `originalPlacement`
    data.originalPlacement = data.placement;

    data.positionFixed = this.options.positionFixed;

    // compute the popper offsets
    data.offsets.popper = getPopperOffsets(this.popper, data.offsets.reference, data.placement);

    data.offsets.popper.position = this.options.positionFixed ? 'fixed' : 'absolute';

    // run the modifiers
    data = runModifiers(this.modifiers, data);

    // the first `update` will call `onCreate` callback
    // the other ones will call `onUpdate` callback
    if (!this.state.isCreated) {
      this.state.isCreated = true;
      this.options.onCreate(data);
    } else {
      this.options.onUpdate(data);
    }
  }

  /**
   * Helper used to know if the given modifier is enabled.
   * @method
   * @memberof Popper.Utils
   * @returns {Boolean}
   */
  function isModifierEnabled(modifiers, modifierName) {
    return modifiers.some(function (_ref) {
      var name = _ref.name,
          enabled = _ref.enabled;
      return enabled && name === modifierName;
    });
  }

  /**
   * Get the prefixed supported property name
   * @method
   * @memberof Popper.Utils
   * @argument {String} property (camelCase)
   * @returns {String} prefixed property (camelCase or PascalCase, depending on the vendor prefix)
   */
  function getSupportedPropertyName(property) {
    var prefixes = [false, 'ms', 'Webkit', 'Moz', 'O'];
    var upperProp = property.charAt(0).toUpperCase() + property.slice(1);

    for (var i = 0; i < prefixes.length; i++) {
      var prefix = prefixes[i];
      var toCheck = prefix ? '' + prefix + upperProp : property;
      if (typeof document.body.style[toCheck] !== 'undefined') {
        return toCheck;
      }
    }
    return null;
  }

  /**
   * Destroys the popper.
   * @method
   * @memberof Popper
   */
  function destroy() {
    this.state.isDestroyed = true;

    // touch DOM only if `applyStyle` modifier is enabled
    if (isModifierEnabled(this.modifiers, 'applyStyle')) {
      this.popper.removeAttribute('x-placement');
      this.popper.style.position = '';
      this.popper.style.top = '';
      this.popper.style.left = '';
      this.popper.style.right = '';
      this.popper.style.bottom = '';
      this.popper.style.willChange = '';
      this.popper.style[getSupportedPropertyName('transform')] = '';
    }

    this.disableEventListeners();

    // remove the popper if user explicitly asked for the deletion on destroy
    // do not use `remove` because IE11 doesn't support it
    if (this.options.removeOnDestroy) {
      this.popper.parentNode.removeChild(this.popper);
    }
    return this;
  }

  /**
   * Get the window associated with the element
   * @argument {Element} element
   * @returns {Window}
   */
  function getWindow(element) {
    var ownerDocument = element.ownerDocument;
    return ownerDocument ? ownerDocument.defaultView : window;
  }

  function attachToScrollParents(scrollParent, event, callback, scrollParents) {
    var isBody = scrollParent.nodeName === 'BODY';
    var target = isBody ? scrollParent.ownerDocument.defaultView : scrollParent;
    target.addEventListener(event, callback, { passive: true });

    if (!isBody) {
      attachToScrollParents(getScrollParent(target.parentNode), event, callback, scrollParents);
    }
    scrollParents.push(target);
  }

  /**
   * Setup needed event listeners used to update the popper position
   * @method
   * @memberof Popper.Utils
   * @private
   */
  function setupEventListeners(reference, options, state, updateBound) {
    // Resize event listener on window
    state.updateBound = updateBound;
    getWindow(reference).addEventListener('resize', state.updateBound, { passive: true });

    // Scroll event listener on scroll parents
    var scrollElement = getScrollParent(reference);
    attachToScrollParents(scrollElement, 'scroll', state.updateBound, state.scrollParents);
    state.scrollElement = scrollElement;
    state.eventsEnabled = true;

    return state;
  }

  /**
   * It will add resize/scroll events and start recalculating
   * position of the popper element when they are triggered.
   * @method
   * @memberof Popper
   */
  function enableEventListeners() {
    if (!this.state.eventsEnabled) {
      this.state = setupEventListeners(this.reference, this.options, this.state, this.scheduleUpdate);
    }
  }

  /**
   * Remove event listeners used to update the popper position
   * @method
   * @memberof Popper.Utils
   * @private
   */
  function removeEventListeners(reference, state) {
    // Remove resize event listener on window
    getWindow(reference).removeEventListener('resize', state.updateBound);

    // Remove scroll event listener on scroll parents
    state.scrollParents.forEach(function (target) {
      target.removeEventListener('scroll', state.updateBound);
    });

    // Reset state
    state.updateBound = null;
    state.scrollParents = [];
    state.scrollElement = null;
    state.eventsEnabled = false;
    return state;
  }

  /**
   * It will remove resize/scroll events and won't recalculate popper position
   * when they are triggered. It also won't trigger `onUpdate` callback anymore,
   * unless you call `update` method manually.
   * @method
   * @memberof Popper
   */
  function disableEventListeners() {
    if (this.state.eventsEnabled) {
      cancelAnimationFrame(this.scheduleUpdate);
      this.state = removeEventListeners(this.reference, this.state);
    }
  }

  /**
   * Tells if a given input is a number
   * @method
   * @memberof Popper.Utils
   * @param {*} input to check
   * @return {Boolean}
   */
  function isNumeric(n) {
    return n !== '' && !isNaN(parseFloat(n)) && isFinite(n);
  }

  /**
   * Set the style to the given popper
   * @method
   * @memberof Popper.Utils
   * @argument {Element} element - Element to apply the style to
   * @argument {Object} styles
   * Object with a list of properties and values which will be applied to the element
   */
  function setStyles(element, styles) {
    Object.keys(styles).forEach(function (prop) {
      var unit = '';
      // add unit if the value is numeric and is one of the following
      if (['width', 'height', 'top', 'right', 'bottom', 'left'].indexOf(prop) !== -1 && isNumeric(styles[prop])) {
        unit = 'px';
      }
      element.style[prop] = styles[prop] + unit;
    });
  }

  /**
   * Set the attributes to the given popper
   * @method
   * @memberof Popper.Utils
   * @argument {Element} element - Element to apply the attributes to
   * @argument {Object} styles
   * Object with a list of properties and values which will be applied to the element
   */
  function setAttributes(element, attributes) {
    Object.keys(attributes).forEach(function (prop) {
      var value = attributes[prop];
      if (value !== false) {
        element.setAttribute(prop, attributes[prop]);
      } else {
        element.removeAttribute(prop);
      }
    });
  }

  /**
   * @function
   * @memberof Modifiers
   * @argument {Object} data - The data object generated by `update` method
   * @argument {Object} data.styles - List of style properties - values to apply to popper element
   * @argument {Object} data.attributes - List of attribute properties - values to apply to popper element
   * @argument {Object} options - Modifiers configuration and options
   * @returns {Object} The same data object
   */
  function applyStyle(data) {
    // any property present in `data.styles` will be applied to the popper,
    // in this way we can make the 3rd party modifiers add custom styles to it
    // Be aware, modifiers could override the properties defined in the previous
    // lines of this modifier!
    setStyles(data.instance.popper, data.styles);

    // any property present in `data.attributes` will be applied to the popper,
    // they will be set as HTML attributes of the element
    setAttributes(data.instance.popper, data.attributes);

    // if arrowElement is defined and arrowStyles has some properties
    if (data.arrowElement && Object.keys(data.arrowStyles).length) {
      setStyles(data.arrowElement, data.arrowStyles);
    }

    return data;
  }

  /**
   * Set the x-placement attribute before everything else because it could be used
   * to add margins to the popper margins needs to be calculated to get the
   * correct popper offsets.
   * @method
   * @memberof Popper.modifiers
   * @param {HTMLElement} reference - The reference element used to position the popper
   * @param {HTMLElement} popper - The HTML element used as popper
   * @param {Object} options - Popper.js options
   */
  function applyStyleOnLoad(reference, popper, options, modifierOptions, state) {
    // compute reference element offsets
    var referenceOffsets = getReferenceOffsets(state, popper, reference, options.positionFixed);

    // compute auto placement, store placement inside the data object,
    // modifiers will be able to edit `placement` if needed
    // and refer to originalPlacement to know the original value
    var placement = computeAutoPlacement(options.placement, referenceOffsets, popper, reference, options.modifiers.flip.boundariesElement, options.modifiers.flip.padding);

    popper.setAttribute('x-placement', placement);

    // Apply `position` to popper before anything else because
    // without the position applied we can't guarantee correct computations
    setStyles(popper, { position: options.positionFixed ? 'fixed' : 'absolute' });

    return options;
  }

  /**
   * @function
   * @memberof Popper.Utils
   * @argument {Object} data - The data object generated by `update` method
   * @argument {Boolean} shouldRound - If the offsets should be rounded at all
   * @returns {Object} The popper's position offsets rounded
   *
   * The tale of pixel-perfect positioning. It's still not 100% perfect, but as
   * good as it can be within reason.
   * Discussion here: https://github.com/FezVrasta/popper.js/pull/715
   *
   * Low DPI screens cause a popper to be blurry if not using full pixels (Safari
   * as well on High DPI screens).
   *
   * Firefox prefers no rounding for positioning and does not have blurriness on
   * high DPI screens.
   *
   * Only horizontal placement and left/right values need to be considered.
   */
  function getRoundedOffsets(data, shouldRound) {
    var _data$offsets = data.offsets,
        popper = _data$offsets.popper,
        reference = _data$offsets.reference;
    var round = Math.round,
        floor = Math.floor;

    var noRound = function noRound(v) {
      return v;
    };

    var referenceWidth = round(reference.width);
    var popperWidth = round(popper.width);

    var isVertical = ['left', 'right'].indexOf(data.placement) !== -1;
    var isVariation = data.placement.indexOf('-') !== -1;
    var sameWidthParity = referenceWidth % 2 === popperWidth % 2;
    var bothOddWidth = referenceWidth % 2 === 1 && popperWidth % 2 === 1;

    var horizontalToInteger = !shouldRound ? noRound : isVertical || isVariation || sameWidthParity ? round : floor;
    var verticalToInteger = !shouldRound ? noRound : round;

    return {
      left: horizontalToInteger(bothOddWidth && !isVariation && shouldRound ? popper.left - 1 : popper.left),
      top: verticalToInteger(popper.top),
      bottom: verticalToInteger(popper.bottom),
      right: horizontalToInteger(popper.right)
    };
  }

  var isFirefox = isBrowser && /Firefox/i.test(navigator.userAgent);

  /**
   * @function
   * @memberof Modifiers
   * @argument {Object} data - The data object generated by `update` method
   * @argument {Object} options - Modifiers configuration and options
   * @returns {Object} The data object, properly modified
   */
  function computeStyle(data, options) {
    var x = options.x,
        y = options.y;
    var popper = data.offsets.popper;

    // Remove this legacy support in Popper.js v2

    var legacyGpuAccelerationOption = find$1(data.instance.modifiers, function (modifier) {
      return modifier.name === 'applyStyle';
    }).gpuAcceleration;
    if (legacyGpuAccelerationOption !== undefined) {
      console.warn('WARNING: `gpuAcceleration` option moved to `computeStyle` modifier and will not be supported in future versions of Popper.js!');
    }
    var gpuAcceleration = legacyGpuAccelerationOption !== undefined ? legacyGpuAccelerationOption : options.gpuAcceleration;

    var offsetParent = getOffsetParent(data.instance.popper);
    var offsetParentRect = getBoundingClientRect(offsetParent);

    // Styles
    var styles = {
      position: popper.position
    };

    var offsets = getRoundedOffsets(data, window.devicePixelRatio < 2 || !isFirefox);

    var sideA = x === 'bottom' ? 'top' : 'bottom';
    var sideB = y === 'right' ? 'left' : 'right';

    // if gpuAcceleration is set to `true` and transform is supported,
    //  we use `translate3d` to apply the position to the popper we
    // automatically use the supported prefixed version if needed
    var prefixedProperty = getSupportedPropertyName('transform');

    // now, let's make a step back and look at this code closely (wtf?)
    // If the content of the popper grows once it's been positioned, it
    // may happen that the popper gets misplaced because of the new content
    // overflowing its reference element
    // To avoid this problem, we provide two options (x and y), which allow
    // the consumer to define the offset origin.
    // If we position a popper on top of a reference element, we can set
    // `x` to `top` to make the popper grow towards its top instead of
    // its bottom.
    var left = void 0,
        top = void 0;
    if (sideA === 'bottom') {
      // when offsetParent is <html> the positioning is relative to the bottom of the screen (excluding the scrollbar)
      // and not the bottom of the html element
      if (offsetParent.nodeName === 'HTML') {
        top = -offsetParent.clientHeight + offsets.bottom;
      } else {
        top = -offsetParentRect.height + offsets.bottom;
      }
    } else {
      top = offsets.top;
    }
    if (sideB === 'right') {
      if (offsetParent.nodeName === 'HTML') {
        left = -offsetParent.clientWidth + offsets.right;
      } else {
        left = -offsetParentRect.width + offsets.right;
      }
    } else {
      left = offsets.left;
    }
    if (gpuAcceleration && prefixedProperty) {
      styles[prefixedProperty] = 'translate3d(' + left + 'px, ' + top + 'px, 0)';
      styles[sideA] = 0;
      styles[sideB] = 0;
      styles.willChange = 'transform';
    } else {
      // othwerise, we use the standard `top`, `left`, `bottom` and `right` properties
      var invertTop = sideA === 'bottom' ? -1 : 1;
      var invertLeft = sideB === 'right' ? -1 : 1;
      styles[sideA] = top * invertTop;
      styles[sideB] = left * invertLeft;
      styles.willChange = sideA + ', ' + sideB;
    }

    // Attributes
    var attributes = {
      'x-placement': data.placement
    };

    // Update `data` attributes, styles and arrowStyles
    data.attributes = _extends({}, attributes, data.attributes);
    data.styles = _extends({}, styles, data.styles);
    data.arrowStyles = _extends({}, data.offsets.arrow, data.arrowStyles);

    return data;
  }

  /**
   * Helper used to know if the given modifier depends from another one.<br />
   * It checks if the needed modifier is listed and enabled.
   * @method
   * @memberof Popper.Utils
   * @param {Array} modifiers - list of modifiers
   * @param {String} requestingName - name of requesting modifier
   * @param {String} requestedName - name of requested modifier
   * @returns {Boolean}
   */
  function isModifierRequired(modifiers, requestingName, requestedName) {
    var requesting = find$1(modifiers, function (_ref) {
      var name = _ref.name;
      return name === requestingName;
    });

    var isRequired = !!requesting && modifiers.some(function (modifier) {
      return modifier.name === requestedName && modifier.enabled && modifier.order < requesting.order;
    });

    if (!isRequired) {
      var _requesting = '`' + requestingName + '`';
      var requested = '`' + requestedName + '`';
      console.warn(requested + ' modifier is required by ' + _requesting + ' modifier in order to work, be sure to include it before ' + _requesting + '!');
    }
    return isRequired;
  }

  /**
   * @function
   * @memberof Modifiers
   * @argument {Object} data - The data object generated by update method
   * @argument {Object} options - Modifiers configuration and options
   * @returns {Object} The data object, properly modified
   */
  function arrow(data, options) {
    var _data$offsets$arrow;

    // arrow depends on keepTogether in order to work
    if (!isModifierRequired(data.instance.modifiers, 'arrow', 'keepTogether')) {
      return data;
    }

    var arrowElement = options.element;

    // if arrowElement is a string, suppose it's a CSS selector
    if (typeof arrowElement === 'string') {
      arrowElement = data.instance.popper.querySelector(arrowElement);

      // if arrowElement is not found, don't run the modifier
      if (!arrowElement) {
        return data;
      }
    } else {
      // if the arrowElement isn't a query selector we must check that the
      // provided DOM node is child of its popper node
      if (!data.instance.popper.contains(arrowElement)) {
        console.warn('WARNING: `arrow.element` must be child of its popper element!');
        return data;
      }
    }

    var placement = data.placement.split('-')[0];
    var _data$offsets = data.offsets,
        popper = _data$offsets.popper,
        reference = _data$offsets.reference;

    var isVertical = ['left', 'right'].indexOf(placement) !== -1;

    var len = isVertical ? 'height' : 'width';
    var sideCapitalized = isVertical ? 'Top' : 'Left';
    var side = sideCapitalized.toLowerCase();
    var altSide = isVertical ? 'left' : 'top';
    var opSide = isVertical ? 'bottom' : 'right';
    var arrowElementSize = getOuterSizes(arrowElement)[len];

    //
    // extends keepTogether behavior making sure the popper and its
    // reference have enough pixels in conjunction
    //

    // top/left side
    if (reference[opSide] - arrowElementSize < popper[side]) {
      data.offsets.popper[side] -= popper[side] - (reference[opSide] - arrowElementSize);
    }
    // bottom/right side
    if (reference[side] + arrowElementSize > popper[opSide]) {
      data.offsets.popper[side] += reference[side] + arrowElementSize - popper[opSide];
    }
    data.offsets.popper = getClientRect(data.offsets.popper);

    // compute center of the popper
    var center = reference[side] + reference[len] / 2 - arrowElementSize / 2;

    // Compute the sideValue using the updated popper offsets
    // take popper margin in account because we don't have this info available
    var css = getStyleComputedProperty(data.instance.popper);
    var popperMarginSide = parseFloat(css['margin' + sideCapitalized], 10);
    var popperBorderSide = parseFloat(css['border' + sideCapitalized + 'Width'], 10);
    var sideValue = center - data.offsets.popper[side] - popperMarginSide - popperBorderSide;

    // prevent arrowElement from being placed not contiguously to its popper
    sideValue = Math.max(Math.min(popper[len] - arrowElementSize, sideValue), 0);

    data.arrowElement = arrowElement;
    data.offsets.arrow = (_data$offsets$arrow = {}, defineProperty(_data$offsets$arrow, side, Math.round(sideValue)), defineProperty(_data$offsets$arrow, altSide, ''), _data$offsets$arrow);

    return data;
  }

  /**
   * Get the opposite placement variation of the given one
   * @method
   * @memberof Popper.Utils
   * @argument {String} placement variation
   * @returns {String} flipped placement variation
   */
  function getOppositeVariation(variation) {
    if (variation === 'end') {
      return 'start';
    } else if (variation === 'start') {
      return 'end';
    }
    return variation;
  }

  /**
   * List of accepted placements to use as values of the `placement` option.<br />
   * Valid placements are:
   * - `auto`
   * - `top`
   * - `right`
   * - `bottom`
   * - `left`
   *
   * Each placement can have a variation from this list:
   * - `-start`
   * - `-end`
   *
   * Variations are interpreted easily if you think of them as the left to right
   * written languages. Horizontally (`top` and `bottom`), `start` is left and `end`
   * is right.<br />
   * Vertically (`left` and `right`), `start` is top and `end` is bottom.
   *
   * Some valid examples are:
   * - `top-end` (on top of reference, right aligned)
   * - `right-start` (on right of reference, top aligned)
   * - `bottom` (on bottom, centered)
   * - `auto-end` (on the side with more space available, alignment depends by placement)
   *
   * @static
   * @type {Array}
   * @enum {String}
   * @readonly
   * @method placements
   * @memberof Popper
   */
  var placements = ['auto-start', 'auto', 'auto-end', 'top-start', 'top', 'top-end', 'right-start', 'right', 'right-end', 'bottom-end', 'bottom', 'bottom-start', 'left-end', 'left', 'left-start'];

  // Get rid of `auto` `auto-start` and `auto-end`
  var validPlacements = placements.slice(3);

  /**
   * Given an initial placement, returns all the subsequent placements
   * clockwise (or counter-clockwise).
   *
   * @method
   * @memberof Popper.Utils
   * @argument {String} placement - A valid placement (it accepts variations)
   * @argument {Boolean} counter - Set to true to walk the placements counterclockwise
   * @returns {Array} placements including their variations
   */
  function clockwise(placement) {
    var counter = arguments.length > 1 && arguments[1] !== undefined ? arguments[1] : false;

    var index = validPlacements.indexOf(placement);
    var arr = validPlacements.slice(index + 1).concat(validPlacements.slice(0, index));
    return counter ? arr.reverse() : arr;
  }

  var BEHAVIORS = {
    FLIP: 'flip',
    CLOCKWISE: 'clockwise',
    COUNTERCLOCKWISE: 'counterclockwise'
  };

  /**
   * @function
   * @memberof Modifiers
   * @argument {Object} data - The data object generated by update method
   * @argument {Object} options - Modifiers configuration and options
   * @returns {Object} The data object, properly modified
   */
  function flip(data, options) {
    // if `inner` modifier is enabled, we can't use the `flip` modifier
    if (isModifierEnabled(data.instance.modifiers, 'inner')) {
      return data;
    }

    if (data.flipped && data.placement === data.originalPlacement) {
      // seems like flip is trying to loop, probably there's not enough space on any of the flippable sides
      return data;
    }

    var boundaries = getBoundaries(data.instance.popper, data.instance.reference, options.padding, options.boundariesElement, data.positionFixed);

    var placement = data.placement.split('-')[0];
    var placementOpposite = getOppositePlacement(placement);
    var variation = data.placement.split('-')[1] || '';

    var flipOrder = [];

    switch (options.behavior) {
      case BEHAVIORS.FLIP:
        flipOrder = [placement, placementOpposite];
        break;
      case BEHAVIORS.CLOCKWISE:
        flipOrder = clockwise(placement);
        break;
      case BEHAVIORS.COUNTERCLOCKWISE:
        flipOrder = clockwise(placement, true);
        break;
      default:
        flipOrder = options.behavior;
    }

    flipOrder.forEach(function (step, index) {
      if (placement !== step || flipOrder.length === index + 1) {
        return data;
      }

      placement = data.placement.split('-')[0];
      placementOpposite = getOppositePlacement(placement);

      var popperOffsets = data.offsets.popper;
      var refOffsets = data.offsets.reference;

      // using floor because the reference offsets may contain decimals we are not going to consider here
      var floor = Math.floor;
      var overlapsRef = placement === 'left' && floor(popperOffsets.right) > floor(refOffsets.left) || placement === 'right' && floor(popperOffsets.left) < floor(refOffsets.right) || placement === 'top' && floor(popperOffsets.bottom) > floor(refOffsets.top) || placement === 'bottom' && floor(popperOffsets.top) < floor(refOffsets.bottom);

      var overflowsLeft = floor(popperOffsets.left) < floor(boundaries.left);
      var overflowsRight = floor(popperOffsets.right) > floor(boundaries.right);
      var overflowsTop = floor(popperOffsets.top) < floor(boundaries.top);
      var overflowsBottom = floor(popperOffsets.bottom) > floor(boundaries.bottom);

      var overflowsBoundaries = placement === 'left' && overflowsLeft || placement === 'right' && overflowsRight || placement === 'top' && overflowsTop || placement === 'bottom' && overflowsBottom;

      // flip the variation if required
      var isVertical = ['top', 'bottom'].indexOf(placement) !== -1;

      // flips variation if reference element overflows boundaries
      var flippedVariationByRef = !!options.flipVariations && (isVertical && variation === 'start' && overflowsLeft || isVertical && variation === 'end' && overflowsRight || !isVertical && variation === 'start' && overflowsTop || !isVertical && variation === 'end' && overflowsBottom);

      // flips variation if popper content overflows boundaries
      var flippedVariationByContent = !!options.flipVariationsByContent && (isVertical && variation === 'start' && overflowsRight || isVertical && variation === 'end' && overflowsLeft || !isVertical && variation === 'start' && overflowsBottom || !isVertical && variation === 'end' && overflowsTop);

      var flippedVariation = flippedVariationByRef || flippedVariationByContent;

      if (overlapsRef || overflowsBoundaries || flippedVariation) {
        // this boolean to detect any flip loop
        data.flipped = true;

        if (overlapsRef || overflowsBoundaries) {
          placement = flipOrder[index + 1];
        }

        if (flippedVariation) {
          variation = getOppositeVariation(variation);
        }

        data.placement = placement + (variation ? '-' + variation : '');

        // this object contains `position`, we want to preserve it along with
        // any additional property we may add in the future
        data.offsets.popper = _extends({}, data.offsets.popper, getPopperOffsets(data.instance.popper, data.offsets.reference, data.placement));

        data = runModifiers(data.instance.modifiers, data, 'flip');
      }
    });
    return data;
  }

  /**
   * @function
   * @memberof Modifiers
   * @argument {Object} data - The data object generated by update method
   * @argument {Object} options - Modifiers configuration and options
   * @returns {Object} The data object, properly modified
   */
  function keepTogether(data) {
    var _data$offsets = data.offsets,
        popper = _data$offsets.popper,
        reference = _data$offsets.reference;

    var placement = data.placement.split('-')[0];
    var floor = Math.floor;
    var isVertical = ['top', 'bottom'].indexOf(placement) !== -1;
    var side = isVertical ? 'right' : 'bottom';
    var opSide = isVertical ? 'left' : 'top';
    var measurement = isVertical ? 'width' : 'height';

    if (popper[side] < floor(reference[opSide])) {
      data.offsets.popper[opSide] = floor(reference[opSide]) - popper[measurement];
    }
    if (popper[opSide] > floor(reference[side])) {
      data.offsets.popper[opSide] = floor(reference[side]);
    }

    return data;
  }

  /**
   * Converts a string containing value + unit into a px value number
   * @function
   * @memberof {modifiers~offset}
   * @private
   * @argument {String} str - Value + unit string
   * @argument {String} measurement - `height` or `width`
   * @argument {Object} popperOffsets
   * @argument {Object} referenceOffsets
   * @returns {Number|String}
   * Value in pixels, or original string if no values were extracted
   */
  function toValue(str, measurement, popperOffsets, referenceOffsets) {
    // separate value from unit
    var split = str.match(/((?:\-|\+)?\d*\.?\d*)(.*)/);
    var value = +split[1];
    var unit = split[2];

    // If it's not a number it's an operator, I guess
    if (!value) {
      return str;
    }

    if (unit.indexOf('%') === 0) {
      var element = void 0;
      switch (unit) {
        case '%p':
          element = popperOffsets;
          break;
        case '%':
        case '%r':
        default:
          element = referenceOffsets;
      }

      var rect = getClientRect(element);
      return rect[measurement] / 100 * value;
    } else if (unit === 'vh' || unit === 'vw') {
      // if is a vh or vw, we calculate the size based on the viewport
      var size = void 0;
      if (unit === 'vh') {
        size = Math.max(document.documentElement.clientHeight, window.innerHeight || 0);
      } else {
        size = Math.max(document.documentElement.clientWidth, window.innerWidth || 0);
      }
      return size / 100 * value;
    } else {
      // if is an explicit pixel unit, we get rid of the unit and keep the value
      // if is an implicit unit, it's px, and we return just the value
      return value;
    }
  }

  /**
   * Parse an `offset` string to extrapolate `x` and `y` numeric offsets.
   * @function
   * @memberof {modifiers~offset}
   * @private
   * @argument {String} offset
   * @argument {Object} popperOffsets
   * @argument {Object} referenceOffsets
   * @argument {String} basePlacement
   * @returns {Array} a two cells array with x and y offsets in numbers
   */
  function parseOffset(offset, popperOffsets, referenceOffsets, basePlacement) {
    var offsets = [0, 0];

    // Use height if placement is left or right and index is 0 otherwise use width
    // in this way the first offset will use an axis and the second one
    // will use the other one
    var useHeight = ['right', 'left'].indexOf(basePlacement) !== -1;

    // Split the offset string to obtain a list of values and operands
    // The regex addresses values with the plus or minus sign in front (+10, -20, etc)
    var fragments = offset.split(/(\+|\-)/).map(function (frag) {
      return frag.trim();
    });

    // Detect if the offset string contains a pair of values or a single one
    // they could be separated by comma or space
    var divider = fragments.indexOf(find$1(fragments, function (frag) {
      return frag.search(/,|\s/) !== -1;
    }));

    if (fragments[divider] && fragments[divider].indexOf(',') === -1) {
      console.warn('Offsets separated by white space(s) are deprecated, use a comma (,) instead.');
    }

    // If divider is found, we divide the list of values and operands to divide
    // them by ofset X and Y.
    var splitRegex = /\s*,\s*|\s+/;
    var ops = divider !== -1 ? [fragments.slice(0, divider).concat([fragments[divider].split(splitRegex)[0]]), [fragments[divider].split(splitRegex)[1]].concat(fragments.slice(divider + 1))] : [fragments];

    // Convert the values with units to absolute pixels to allow our computations
    ops = ops.map(function (op, index) {
      // Most of the units rely on the orientation of the popper
      var measurement = (index === 1 ? !useHeight : useHeight) ? 'height' : 'width';
      var mergeWithPrevious = false;
      return op
      // This aggregates any `+` or `-` sign that aren't considered operators
      // e.g.: 10 + +5 => [10, +, +5]
      .reduce(function (a, b) {
        if (a[a.length - 1] === '' && ['+', '-'].indexOf(b) !== -1) {
          a[a.length - 1] = b;
          mergeWithPrevious = true;
          return a;
        } else if (mergeWithPrevious) {
          a[a.length - 1] += b;
          mergeWithPrevious = false;
          return a;
        } else {
          return a.concat(b);
        }
      }, [])
      // Here we convert the string values into number values (in px)
      .map(function (str) {
        return toValue(str, measurement, popperOffsets, referenceOffsets);
      });
    });

    // Loop trough the offsets arrays and execute the operations
    ops.forEach(function (op, index) {
      op.forEach(function (frag, index2) {
        if (isNumeric(frag)) {
          offsets[index] += frag * (op[index2 - 1] === '-' ? -1 : 1);
        }
      });
    });
    return offsets;
  }

  /**
   * @function
   * @memberof Modifiers
   * @argument {Object} data - The data object generated by update method
   * @argument {Object} options - Modifiers configuration and options
   * @argument {Number|String} options.offset=0
   * The offset value as described in the modifier description
   * @returns {Object} The data object, properly modified
   */
  function offset(data, _ref) {
    var offset = _ref.offset;
    var placement = data.placement,
        _data$offsets = data.offsets,
        popper = _data$offsets.popper,
        reference = _data$offsets.reference;

    var basePlacement = placement.split('-')[0];

    var offsets = void 0;
    if (isNumeric(+offset)) {
      offsets = [+offset, 0];
    } else {
      offsets = parseOffset(offset, popper, reference, basePlacement);