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JavaScript中循環遍歷Array與Map的方法小結
編輯:JavaScript基礎知識     

js循環數組各種方法
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map,獲取所有的key和value
eg1:

//Page地址 
 pageUrl : { 
  menu   : "loadPage.htm?url=/collect/menu.page",   // 進入菜單頁面 
  guangfaPage  : "loadPage.htm?url=/collect/menu.page",   // 進入廣發信息收集頁面 
  pinganPage  : "loadPage.htm?url=/collect/menu.page",   // 進入平安信息收集頁面 
  nuonuoPage  : "loadPage.htm?url=/collect/menu.page",   // 進入諾諾信息收集頁面 
  youbangPage  : "loadPage.htm?url=/collect/menu.page",   // 進入友邦信息收集頁面 
  inputMobileNo : "loadPage.htm?url=/collect/inputMobileNo.page", // 進入輸入手機號頁面 
  readIdCard  : "loadPage.htm?url=/collect/readIdCard.page",  // 進入讀取身份證頁面 
  member   : "loadPage.htm?url=/collect/member.page",   // 進入輸入會員卡號頁面 
  bankCard  : "loadPage.htm?url=/collect/bankCard.page",   // 進入插入銀行卡頁面 
  url   : "loadPage.htm?url=/collect/url.page"    // 進入跳轉url頁面 
 }, 
 
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
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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