Function normalizeKeyframes

src/normalize-keyframes.js:220–312

(effectInput)

  };

  function normalizeKeyframes(effectInput) {
    if (effectInput == null) {
      return [];
    }

    if (window.Symbol && Symbol.iterator && Array.prototype.from && effectInput[Symbol.iterator]) {
      // Handle custom iterables in most browsers by converting to an array
      effectInput = Array.from(effectInput);
    }

    if (!Array.isArray(effectInput)) {
      effectInput = convertToArrayForm(effectInput);
    }

    var keyframes = effectInput.map(function(originalKeyframe) {
      var keyframe = {};
      for (var member in originalKeyframe) {
        var memberValue = originalKeyframe[member];
        if (member == 'offset') {
          if (memberValue != null) {
            memberValue = Number(memberValue);
            if (!isFinite(memberValue))
              throw new TypeError('Keyframe offsets must be numbers.');
            if (memberValue < 0 || memberValue > 1)
              throw new TypeError('Keyframe offsets must be between 0 and 1.');
          }
        } else if (member == 'composite') {
          if (memberValue == 'add' || memberValue == 'accumulate') {
            throw {
              type: DOMException.NOT_SUPPORTED_ERR,
              name: 'NotSupportedError',
              message: 'add compositing is not supported'
            };
          } else if (memberValue != 'replace') {
            throw new TypeError('Invalid composite mode ' + memberValue + '.');
          }
        } else if (member == 'easing') {
          memberValue = shared.normalizeEasing(memberValue);
        } else {
          memberValue = '' + memberValue;
        }
        expandShorthandAndAntiAlias(member, memberValue, keyframe);
      }
      if (keyframe.offset == undefined)
        keyframe.offset = null;
      if (keyframe.easing == undefined)
        keyframe.easing = 'linear';
      return keyframe;
    });

    var everyFrameHasOffset = true;
    var looselySortedByOffset = true;
    var previousOffset = -Infinity;
    for (var i = 0; i < keyframes.length; i++) {
      var offset = keyframes[i].offset;
      if (offset != null) {
        if (offset < previousOffset) {
          throw new TypeError('Keyframes are not loosely sorted by offset. Sort or specify offsets.');