forEach 没有返回值，map 有返回值。
if ( !Array.prototype.forEach ) {Array.prototype.forEach = function forEach( callback, thisArg ) {
var T, k
if ( this == null ) {
throw new TypeError( "this is null or not defined" )
}
var O = Object(this)
var len = O.length >>> 0
if ( typeof callback !== "function" ) {
throw new TypeError( callback + " is not a function" )
}
if ( arguments.length > 1 ) {
T = thisArg
}
k = 0
while( k < len ) {
var kValue
if ( k in O ) {
kValue = O[ k ]
callback.call( T, kValue, k, O )
}
k++
}
}
}
if (!Array.prototype.map) {
Array.prototype.map = function(callback, thisArg) {
var T, A, k
if (this == null) {
throw new TypeError(" this is null or not defined")
}
var O = Object(this)
var len = O.length >>> 0
if (typeof callback !== "function") {
throw new TypeError(callback + " is not a function")
}
if (thisArg) {
T = thisArg
}
A = new Array(len)
k = 0
while(k < len) {
var kValue, mappedValue
if (k in O) {
kValue = O[ k ]
mappedValue = callback.call(T, kValue, k, O)
A[ k ] = mappedValue
}
k++
}
return A
}
}
使用JS写个Map很容易,但是想要HashMap估计有困难.不知道你是否只是想要个Map还是指定HashMap.以下代码是一个普通的Map:function Map() {
var struct = function(key, value) {
this.key = key
this.value = value
}
var put = function(key, value){
for (var i = 0i <this.arr.lengthi++) {
if ( this.arr[i].key === key ) {
this.arr[i].value = value
return
}
}
this.arr[this.arr.length] = new struct(key, value)
}
var get = function(key) {
for (var i = 0i <this.arr.lengthi++) {
if ( this.arr[i].key === key ) {
return this.arr[i].value
}
}
return null
}
var remove = function(key) {
var v
for (var i = 0i <this.arr.lengthi++) {
v = this.arr.pop()
if ( v.key === key ) {
continue
}
this.arr.unshift(v)
}
}
var size = function() {
return this.arr.length
}
var isEmpty = function() {
return this.arr.length <= 0
}
this.arr = new Array()
this.get = get
this.put = put
this.remove = remove
this.size = size
this.isEmpty = isEmpty
}
