Extend without foreach

JavaScript performance comparison

Test case created by Shane O'Sullivan

Preparation code


      
      <script>
Benchmark.prototype.setup = function() {
  var slice = Array.prototype.slice;
  var breaker = {};
  
  var each = function(obj, iterator, context) {
    if (obj.length === +obj.length) {
      for (var i = 0, l = obj.length; i < l; i++) {
        if (i in obj && iterator.call(context, obj[i], i, obj) === breaker) return;
      }
    }
  };
  
  var origExtend = function(obj) {
    each(slice.call(arguments, 1), function(source) {
      for (var prop in source) {
        if (source[prop] !== void 0) obj[prop] = source[prop];
      }
    });
    return obj;
  }
  
  var inlineExtend = function(obj) {
    var len = arguments.length;
    var source;
    var prop;
    for (var i = 1; i < len; i++) {
      source = arguments[i];
      for (prop in source) {
        if (source[prop] !== void 0) obj[prop] = source[prop];
      }
    }
    return obj;
  }
  
  var dest = {};
  var src = {
    a: 'b',
    c: 'd'
  };

};
</script>

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Testing in CCBot 2.0.0 / Other 0.0.0
Test Ops/sec
Extend + each
origExtend(dest, src)
pending…
Extend + inline
inlineExtend(dest, src)
pending…

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