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其他参考手册

CSSStyleDeclaration JS 类型转换


JavaScript 数组 map() 方法


实例

返回原始数组中所有值的平方根的数组:

var numbers = [4, 9, 16, 25];
var x = numbers.map(Math.sqrt)
document.getElementById("demo").innerHTML = x;
亲自试一试 »

页面下方有更多实例。


定义和用法

map() 方法使用为每个数组元素调用函数的结果创建新数组。

map() 方法按顺序为数组中的每个元素调用一次提供的函数。

注释:map() 对没有值的数组元素不执行函数。

注释:map() 不会改变原始数组。


浏览器支持

表中的数字表示支持该方法的第一个浏览器版本。

方法
map() Yes 9.0 1.5 Yes Yes

语法

array.map(function(currentValue, index, arr), thisValue)

参数值

参数 描述
currentValue 必需。当前元素的值。
index 可选。当前元素的数组索引。
arr 可选。当前元素所属的数组对象
thisValue

可选。要传递给函数以用作其 "this" 值的值。

如果此参数为空,则值 "undefined" 将作为其 "this" 值传递。



技术细节

返回值: 数组,包含为原始数组中的每个元素调用提供的函数的结果。
JavaScript 版本: ECMAScript 5

更多实例

实例

将数组中的所有值乘以 10:

var numbers = [65, 44, 12, 4];
var newarray = numbers.map(myFunction)

function myFunction(num) {
  return num * 10;
}

document.getElementById("demo").innerHTML = newarray;
亲自试一试 »

实例

获取数组中每个人的全名:

var persons = [
  {firstname : "Malcom", lastname: "Reynolds"},
  {firstname : "Kaylee", lastname: "Frye"},
  {firstname : "Jayne", lastname: "Cobb"}
];


function getFullName(item) {
  var fullname = [item.firstname,item.lastname].join(" ");
  return fullname;
}

function myFunction() {
  document.getElementById("demo").innerHTML = persons.map(getFullName);
}
亲自试一试 »

相关页面

JavaScript 教程: JavaScript 数组

JavaScript 教程: JavaScript 数组迭代