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(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;
  }
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