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JavaScript中循環(huán)遍歷Array與Map的方法小結(jié)

 更新時(shí)間：2016年03月12日 17:20:06   作者：qiaolevip  
這篇文章主要介紹了JavaScript中循環(huán)遍歷Array與Map的各種方法,利用的都是js入門(mén)學(xué)習(xí)中的基礎(chǔ)知識(shí),需要的朋友可以參考下

js循環(huán)數(shù)組各種方法
eg1：

for (var i = 0; i < myStringArray.length; i++) { 
 alert(myStringArray[i]); 
 //Do something 
}


eg2：

Array.prototype.foo = "foo!"; 
var array = ['a', 'b', 'c']; 
 
for (var i in array) { 
 alert(array[i]); 
} 
 
for(var i in this.$GLOBAL_DETAIL.album_photo_ids){if(this.$GLOBAL_DETAIL.album_photo_ids[i] == "3487675024077108") alert(this.$GLOBAL_DETAIL.album_photo_ids[i]);}

eg3：

[1,2,3,4].map( function(item) { 
   alert(item); 
})


eg4：

var x = [1,2,3,4].map( function(item) { return item * 10; } ); 
 
// And now x is [10,20,30,40]


eg5：

var myStringArray = [ "Hello", "World" ] 
var len = myStringArray.length 
for (var i=0; i<len; ++i) { 
 if (i in myStringArray) { 
 var s = myStringArray[i]; 
 ... do something with s ... 
 } 
}


eg6：

var myStringArray = [ "Hello", "World" ] 
myStringArray.forEach( function(s) { 
  ... do something with s ... 
} )


eg7：

var i=0,item,items = ['one','two','three']; 
while(item=items[i++]){ 
 console.log(item); 
} 
 
// logs: 'one','two','three' 
 
and for the reverse order, an even more efficient loop 
var items = ['one','two','three'], i=items.length; 
while(i--){ 
 console.log(items[i]); 
} 
 
// logs: 'three','two','one' 
 
or the classical for loop 
var items = ['one','two','three'] 
for(var i=0,l=items.length; i < l ; i++){ 
 console.log(items[i]); 
} 
 
// logs: 'one','two','three'


eg8：

var myStringArray = ['Hello', 'World']; // array uses [] not {} 
for (var i in myStringArray) { 
 console.log(i + ' -> ' + myStringArray[i]); // i is the index/key, not the item 
}

js循環(huán)map，獲取所有的key和value
eg1：

//Page地址 
 pageUrl : { 
  menu   : "loadPage.htm?url=/collect/menu.page",   // 進(jìn)入菜單頁(yè)面 
  guangfaPage  : "loadPage.htm?url=/collect/menu.page",   // 進(jìn)入廣發(fā)信息收集頁(yè)面 
  pinganPage  : "loadPage.htm?url=/collect/menu.page",   // 進(jìn)入平安信息收集頁(yè)面 
  nuonuoPage  : "loadPage.htm?url=/collect/menu.page",   // 進(jìn)入諾諾信息收集頁(yè)面 
  youbangPage  : "loadPage.htm?url=/collect/menu.page",   // 進(jìn)入友邦信息收集頁(yè)面 
  inputMobileNo : "loadPage.htm?url=/collect/inputMobileNo.page", // 進(jìn)入輸入手機(jī)號(hào)頁(yè)面 
  readIdCard  : "loadPage.htm?url=/collect/readIdCard.page",  // 進(jìn)入讀取身份證頁(yè)面 
  member   : "loadPage.htm?url=/collect/member.page",   // 進(jìn)入輸入會(huì)員卡號(hào)頁(yè)面 
  bankCard  : "loadPage.htm?url=/collect/bankCard.page",   // 進(jìn)入插入銀行卡頁(yè)面 
  url   : "loadPage.htm?url=/collect/url.page"    // 進(jìn)入跳轉(zhuǎn)url頁(yè)面 
 }, 
 
for(var key in this.pageUrl){ 
 alert(key+" : "+this.pageUrl[key]); 
}


eg2：

var obj = { 
 "a": 1, 
 "b": 2, 
 "c": 3 
}; 
 
for (var prop in obj) { 
 if (obj.hasOwnProperty(prop)) { 
 // or if (Object.prototype.hasOwnProperty.call(obj,prop)) for safety... 
 alert("prop: " + prop + " value: " + obj[prop]) 
 } 
}


雙重Map循環(huán)
eg：

var msg = ""; 
for(var key in Pin) { 
 for(var i in Pin[key]){ 
 msg+=i+": "+Pin[key][i]+"\n"; 
 } 
} 
alert(msg);

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