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其他参考手册

CSSStyleDeclaration JS 类型转换


JavaScript 字符串 charCodeAt() 方法

实例

返回字符串中第一个字符的 Unicode(Unicode值表示"H"):

var str = "HELLO WORLD";
var n = str.charCodeAt(0);

亲自试一试 »

页面下方有更多实例。


定义和用法

charCodeAt() 方法返回字符串中指定索引处字符的Unicode。

第一个字符的索引为0,第二个字符的索引为1,依此类推。

提示: 可以将 charCodeAt() 方法与 length 属性一起使用,以返回字符串中最后一个字符的 Unicode。最后一个字符的索引为-1,第二个字符的索引为-2,依此类推(参见下面的示例)。

提示: 有关Unicode字符集的更多信息,请访问 HTML 字符集参考


浏览器支持

方法
charCodeAt() Yes Yes Yes Yes Yes

语法

string.charCodeAt(index)

参数值

参数 描述
index 可选。表示要返回的字符索引的数字。如果未指定,则默认值为0


技术细节

返回值: 数字,表示指定索引处字符的 unicode。

注释: 如果指定的索引中没有字符,或者索引小于"0",则此方法返回"NaN"。
JavaScript 版本: ECMAScript 1

更多实例

实例

返回字符串中最后一个字符的 Unicode 值("D"的 Unicode 值):

var str = "HELLO WORLD";
var n = str.charCodeAt(str.length-1);
亲自试一试 »