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JavaScript 數組map()方法建立一個新的數組使用調用此數組中的每個元素上所提供的函數的結果。
文法
array.map(callback[, thisObject]);
下面是參數的詳細資料：
傳回值:
返回建立數組
相容性：
這種方法是一個JavaScript擴充到ECMA-262標準;因此它可能不存在在標準的其他實現。為了使它工作，你需要添加下面的指令碼代碼在頂部：
if (!Array.prototype.map){ Array.prototype.map = function(fun /*, thisp*/) { var len = this.length; if (typeof fun != "function") throw new TypeError(); var res = new Array(len); var thisp = arguments[1]; for (var i = 0; i < len; i++) { if (i in this) res[i] = fun.call(thisp, this[i], i, this); } return res; };}
例子：
<html><head><title>JavaScript Array map Method</title></head><body><script type="text/javascript">if (!Array.prototype.map){ Array.prototype.map = function(fun /*, thisp*/) { var len = this.length; if (typeof fun != "function") throw new TypeError(); var res = new Array(len); var thisp = arguments[1]; for (var i = 0; i < len; i++) { if (i in this) res[i] = fun.call(thisp, this[i], i, this); } return res; };}var numbers = [1, 4, 9];var roots = numbers.map(Math.sqrt);document.write("roots is : " + roots ); </script></body></html>
這將產生以下結果：
roots is : 1,2,3
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