标签：style blog io java ar for 2014 div sp
ECMAScript5新增的数组方法看似都比较简单其实还是有一些细节需要了解的var a = new Array(10);
a[0] = null ;
a[1] = undefined;
var _a = a.map(function(){
return 1;
});
console.info(a);//[ null, undefined, , , , , , , , , ]
console.info(_a);//[ 1, 1, , , , , , , , , ]
_a = a.filter(function(){
return true;
});
console.info(_a);//[ null, undefined ]var each = Array.prototype.forEach ? Array.prototype.forEach : function(callback) {
var arr=this;
for (var i in arr) {
var item = arr[i];
callback.call(item, item, i, arr);
}
}
Array.prototype.each = each;
var map = Array.prototype.map ? Array.prototype.map : function(callback) {
var arr = this;
var _arr = arr.slice(0);
for (var i in arr) {
var item = arr[i]
_arr[i] = callback(item, item);
}
return _arr;
}
Array.prototype.map = map;
var filter= Array.prototype.filter ? Array.prototype.filter : function(callback) {
var r = [];
var arr = this;
for (var i in arr) {
var item = arr[i];
if(callback.call(item, item)) {
r.push(item);
}
}
return r;
}
Array.prototype.filter = filter;标签：style blog io java ar for 2014 div sp
原文地址：http://blog.csdn.net/songzheng_741/article/details/39459239
