JavaScript中循环遍历Array与Map的方法小结

js循环数组各种方法
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循环map，获取所有的key和value
eg1：

//Page地址pageUrl : { menu : "loadPage.htm?url=/collect/menu.page", // 进入菜单页面 guangfaPage: "loadPage.htm?url=/collect/menu.page", // 进入广发信息收集页面 pinganPage: "loadPage.htm?url=/collect/menu.page", // 进入平安信息收集页面 nuonuoPage: "loadPage.htm?url=/collect/menu.page", // 进入诺诺信息收集页面 youbangPage: "loadPage.htm?url=/collect/menu.page", // 进入友邦信息收集页面 inputMobileNo : "loadPage.htm?url=/collect/inputMobileNo.page", // 进入输入手机号页面 readIdCard: "loadPage.htm?url=/collect/readIdCard.page",// 进入读取身份证页面 member : "loadPage.htm?url=/collect/member.page", // 进入输入会员卡号页面 bankCard: "loadPage.htm?url=/collect/bankCard.page", // 进入插入银行卡页面 url : "loadPage.htm?url=/collect/url.page"// 进入跳转url页面},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]）} }

双重Map循环
eg：

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