关于array的性能优化

 

/*
*keys-get a array contains all the keys in object*
*@function*
*@param {Object} source*
*@return {Array}*
*/
ZYC.object.keys = function(source){
    var result=[],key,_length=0; 
    for(key in source){
	   if(source.hasOwnProperty(key)){
	      result[_length++] = key;
	   }
	}
    return result;
};

//往array里面push可以用result[_length++] 来替代