blob: f75e5eabdb41342011c2ca82e7eb993bfc19f2a0 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
|
---
title: String.length
slug: Web/JavaScript/Reference/Global_Objects/String/length
tags:
- JavaScript
- Property
- Prototype
- String
translation_of: Web/JavaScript/Reference/Global_Objects/String/length
---
<p>{{JSRef("Global_Objects", "String")}}</p>
<h2 id="Summary">概述</h2>
<p><strong>length</strong> 属性表示一个字符串的长度。</p>
<h2 id="Description">描述</h2>
<p>该属性返回字符串中字符编码单元的数量。JavaScript 使用 {{ interwiki("wikipedia", "UTF-16") }} 编码，该编码使用一个 16 比特的编码单元来表示大部分常见的字符，使用两个代码单元表示不常用的字符。因此 length 返回值可能与字符串中实际的字符数量不相同。</p>
<p>空字符串的 <code>length</code> 为 0。</p>
<p>静态属性 <strong>String.length</strong> 返回 1。</p>
<h2 id="Examples">示例</h2>
<pre class="brush: js">var x = "Mozilla";
var empty = "";
console.log("Mozilla is " + x.length + " code units long");
/* "Mozilla is 7 code units long" */
console.log("The empty string is has a length of " + empty.length);
/* "The empty string is has a length of 0" */</pre>
<h2 id="规范">规范</h2>
<table class="standard-table">
<tbody>
<tr>
<th scope="col">Specification</th>
<th scope="col">Status</th>
<th scope="col">Comment</th>
</tr>
<tr>
<td>{{SpecName('ES1')}}</td>
<td>{{Spec2('ES1')}}</td>
<td>Initial definition. Implemented in JavaScript 1.0.</td>
</tr>
<tr>
<td>{{SpecName('ES5.1', '#sec-15.5.5.1', 'String.prototype.length')}}</td>
<td>{{Spec2('ES5.1')}}</td>
<td> </td>
</tr>
<tr>
<td>{{SpecName('ES6', '#sec-properties-of-string-instances-length', 'String.prototype.length')}}</td>
<td>{{Spec2('ES6')}}</td>
<td> </td>
</tr>
</tbody>
</table>
<h2 id="浏览器兼容性">浏览器兼容性</h2>
{{Compat}}
<h2 id="See_also">相关链接</h2>
<ul>
<li><a class="external external-icon" href="http://developer.teradata.com/blog/jasonstrimpel/2011/11/javascript-string-length-and-internationalizing-web-applications">JavaScript String.length and Internationalizing Web Applications</a></li>
</ul>
|
