JS for...in 循环详解-优快云博客

本文介绍了JavaScript中for...in循环的用法及语法结构，通过实例演示了如何利用for...in循环遍历数组元素及对象属性，并强调了循环体内的代码会针对每个元素或属性执行一次。

The for...in statement is used to loop (iterate) through the elements of an array or through the properties of an object.
for...in声明通过一组元素或对象属性进行循环（重复）

Examples
举例

For...In statement
How to use a for...in statement to loop through the elements of an array.
怎样通过一组元素来使用for...in声明进行循环

JavaScript For...In Statement
JS的for...in声明

The for...in statement is used to loop (iterate) through the elements of an array or through the properties of an object.
和第一句重复了（-_-!!）

The code in the body of the for ... in loop is executed once for each element/property.
在for...in循环躯干部分里的代码针对每个元素/属性执行一次

Syntax
语法

for (variable in object)
{
    code to be executed
}

The variable argument can be a named variable, an array element, or a property of an object.
变量可以是数组或是对象的属性

Example
举例

Using for...in to loop through an array:
数组使用for...in循环

<html>

<body>

<script type="text/javascript">
var x
var mycars = new Array()
mycars[0] = "Saab"
mycars[1] = "Volvo"
mycars[2] = "BMW"

for (x in mycars)
{
document.write(mycars[x] + "<br />")
}

</script>