JavaScript Best Practices: Arrays

  • Use the literal syntax for array creation.
    // bad
    var items = new Array();
    
    // good
    var items = [];
    
  • Use Array#push instead of direct assignment to add items to an array.
    var someStack = [];
    
    
    // bad
    someStack[someStack.length] = 'abracadabra';
    
    // good
    someStack.push('abracadabra');
    
  • When you need to copy an array use Array#slice. jsPerf
    var len = items.length;
    var itemsCopy = [];
    var i;
    
    // bad
    for (i = 0; i < len; i++) {
      itemsCopy[i] = items[i];
    }
    
    // good
    itemsCopy = items.slice();
    
  • To convert an array-like object to an array, use Array#slice.
    function trigger() {
      var args = Array.prototype.slice.call(arguments);
      ...
    }
    

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