Function canonicalize

src/diff.js:476–541

(obj, stack, replacementStack, replacer, key)

  // object that is already on the "stack" of items being processed. Accepts an optional replacer

  function canonicalize(obj, stack, replacementStack, replacer, key) {
    stack = stack || [];
    replacementStack = replacementStack || [];

    if (replacer) {
      obj = replacer(key, obj);
    }

    var i;

    for (i = 0; i < stack.length; i += 1) {
      if (stack[i] === obj) {
        return replacementStack[i];
      }
    }

    var canonicalizedObj;

    if ('[object Array]' === objectPrototypeToString.call(obj)) {
      stack.push(obj);
      canonicalizedObj = new Array(obj.length);
      replacementStack.push(canonicalizedObj);

      for (i = 0; i < obj.length; i += 1) {
        canonicalizedObj[i] = canonicalize(obj[i], stack, replacementStack, replacer, key);
      }

      stack.pop();
      replacementStack.pop();
      return canonicalizedObj;
    }

    if (obj && obj.toJSON) {
      obj = obj.toJSON();
    }

    if (_typeof(obj) === 'object' && obj !== null) {
      stack.push(obj);
      canonicalizedObj = {};
      replacementStack.push(canonicalizedObj);

      var sortedKeys = [],
          _key;

      for (_key in obj) {
        /* istanbul ignore else */
        if (obj.hasOwnProperty(_key)) {
          sortedKeys.push(_key);
        }
      }

      sortedKeys.sort();

      for (i = 0; i < sortedKeys.length; i += 1) {
        _key = sortedKeys[i];
        canonicalizedObj[_key] = canonicalize(obj[_key], stack, replacementStack, replacer, _key);
      }