JavaScript中Array的实用操作技巧分享

var arr = new Array(); //[]
var brr = Array();  //[] 两者等效

var arr = Array(3); //[]
arr.length;   //3 长度为3的空数组

var arr = Array(22,33,'qq',{}); //[22, 33, "qq", Object]
var brr = [22,33,'qq',{}];  //同上

var a = [];
typeof a;   //object
Array.isArray(a); //true

var arr = Array(22,33,'qq',{});
arr.push('weibo');    //5
arr       //[22, 33, "qq", {}, "weibo"]

var a = [22,33];
var b = [44,55];

Array.prototype.push.apply(a, b)
// 或者
a.push.apply(a, b)
// 或者
a.push(44,55);   //此时的数组a = [22,33,44,55];

a.push(b);
a;      //[22,33,[44,55]]
a.length;     // 3 !!
console.log(a);   //[22, 33, Array[2]]

var a = [
 {name: 'Stark', value: 'Ironman'},
 {name: 'Cap' , value: 'Oldman'}
];
var b = [
 {name: 'Jerry', email: 'Jerry@qq.com'},
 {name: 'Lory' , email: 'Lory@163.com'},
 {name: 'susan', email: 'susan@gmail.com'}
];
//错误写法
a.push(b);   //3
console.log(a);  //[Object, Object, Array[3]]
//正确写法
a.push.apply(a.b); //5
console.log(a);  //[Object, Object, Object, Object, Object]

var a = ['qq', 'weibo', 'weixin'];
a.pop();        // 'weixin'
a;         // ['qq', 'weibo']

var a = [1, 2, 3, 4];
a.join(' ')  // '1 2 3 4'
a.join(' | ')  // "1 | 2 | 3 | 4"
var b = a.join() // "1,2,3,4"
console.log(a); // [1, 2, 3, 4]
console.log(b); // "1,2,3,4"

var a = [22,33];
var b = [44,55];
var c = a.concat(b);
console.log(a);  //[22, 33]
console.log(b);  //[44, 55]
console.log(c);  //[22, 33, 44, 55]

var a = [{name: 'tom', email: 'tom@example.com'},
   {name: 'peter', email: 'peter@163.com'}];
var b = [{name: 'Jerry', email: 'Jerry@qq.com'},
   {name: 'Lory', email: 'Lory@dfl.com'},
   {name: 'susan', value: 'susan@gmail.com'}];
var c = a.concat(b);
c;   // [{name: 'tom', email: 'tom@example.com'},
   // {name: 'peter', email: 'peter@163.com'},
   // {name: 'Jerry', email: 'Jerry@qq.com'},
   // {name: 'Lory', email: 'Lory@dfl.com'},
   // {name: 'susan', value: 'susan@gmail.com'}]

var numbers = [1, 2, 3];
var num  = numbers.map(function (n) {  // [2, 4, 6]
     return n * 2;
    });
numbers;          //[1,2,3]

var brr = [1, 2, 3].map( function(elem, index, arr) {
 return elem * index;
});
brr; // [0, 2, 6]

var arr = ['a', 'b', 'c'];

var brr = [0, 2].map(function(e){
 return this[e];
}, arr)
brr; // ['a', 'c']

var b = [
 {name: 'Jerry', email: 'Jerry@qq.com'},
 {name: 'Lory', email: 'Lory@dfl.com'},
 {name: 'susan', value: 'susan@gmail.com'}];
 
var url = b.
   map(function(n){
    return n.name + "=" + n.email
   })
   .join("&");
   
console.log(url); 
   //Jerry=Jerry@qq.com&Lory=Lory@dfl.com&susan=susan@gmail.com

var endURL = "localhost:8080/XXXX/" + eventAction + "!" + operation + ""
    + url;