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String.prototype.localeCompare()

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语法
1. 参数
描述
示例
性能相关
规范
浏览器支持
相关链接

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localeCompare() 方法返回一个数字来表明调用该函数的字符串（reference string）的排列顺序是否在某个给定的字符串的前面或者后面，或者是一样的（编码中的位置）。

新的 locales 、 options 参数能让应用程序定制函数的行为即指定用来排序的语言。 locales 和 options 参数是依赖于具体实现的，在旧的实现中这两个参数是完全被忽略的。

语法

referenceStr.localeCompare(compareString[, locales[, options]])

参数

查阅浏览器支持部分来确定哪些浏览器支持 locales 参数和 options 参数，在功能检测中检查对 locales 、options 参数的支持。

compareString: 用来比较的字符串

locales

Optional. A string with a BCP 47 language tag, or an array of such strings. For the general form and interpretation of the locales argument, see the Intl page. The following Unicode extension keys are allowed:

co: Variant collations for certain locales. Possible values include: "big5han", "dict", "direct", "ducet", "gb2312", "phonebk", "phonetic", "pinyin", "reformed", "searchjl", "stroke", "trad", "unihan". The "standard" and "search" values are ignored; they are replaced by the options property usage (see below).
kn: Whether numeric collation should be used, such that "1" < "2" < "10". Possible values are "true" and "false". This option can be set through an options property or through a Unicode extension key; if both are provided, the options property takes precedence.
kf: Whether upper case or lower case should sort first. Possible values are "upper", "lower", or "false" (use the locale's default). This option can be set through an options property or through a Unicode extension key; if both are provided, the options property takes precedence.

options

Optional. An object with some or all of the following properties:

localeMatcher

The locale matching algorithm to use. Possible values are "lookup" and "best fit"; the default is "best fit". For information about this option, see the Intl page.

usage

Whether the comparison is for sorting or for searching for matching strings. Possible values are "sort" and "search"; the default is "sort".

sensitivity

Which differences in the strings should lead to non-zero result values. Possible values are:

"base": Only strings that differ in base letters compare as unequal. Examples: a ≠ b, a = á, a = A.
"accent": Only strings that differ in base letters or accents and other diacritic marks compare as unequal. Examples: a ≠ b, a ≠ á, a = A.
"case": Only strings that differ in base letters or case compare as unequal. Examples: a ≠ b, a = á, a ≠ A.
"variant": Strings that differ in base letters, accents and other diacritic marks, or case compare as unequal. Other differences may also be taken into consideration. Examples: a ≠ b, a ≠ á, a ≠ A.

The default is "variant" for usage "sort"; it's locale dependent for usage "search".

ignorePunctuation

Whether punctuation should be ignored. Possible values are true and false; the default is false.

numeric

Whether numeric collation should be used, such that "1" < "2" < "10". Possible values are true and false; the default is false. This option can be set through an options property or through a Unicode extension key; if both are provided, the options property takes precedence. Implementations are not required to support this property.

caseFirst

Whether upper case or lower case should sort first. Possible values are "upper", "lower", or "false" (use the locale's default); the default is "false". This option can be set through an options property or through a Unicode extension key; if both are provided, the options property takes precedence. Implementations are not required to support this property.

描述

返回一个数字来表明 referenceStr 是否出现在 compareStr 的前面或者后面，或者是相同位置的。

当 referenceStr 在 compareStr 前面时返回负数
当 referenceStr 作 compareStr 后面时返回正数
相同位置时返回0

切勿依赖于-1或1这样特定的返回值。不同浏览器之间（以及不同浏览器版本之间）返回的正负数的值各有不同，因为W3C规范中只要求返回值是正值和负值，而没有规定具体的值。一些浏览器可能返回-2或2或其他一些负的、正的值。

示例

使用 `localeCompare()`

// The letter "a" is before "c" yielding a negative value
'a'.localeCompare('c'); // -2 or -1 (or some other negative value)

// Alphabetically the word "check" comes after "against" yielding a positive value
'check'.localeCompare('against'); // 2 or 1 (or some other positive value)

// "a" and "a" are equivalent yielding a neutral value of zero
'a'.localeCompare('a'); // 0

检查浏览器对扩展参数的支持

locales 和 options 参数还没有被所有阅览器所支持。检查是否被支持，使用 "i" 参数 (a requirement that illegal language tags are rejected) 判断是否有异常 RangeError抛出:

function localeCompareSupportsLocales() {
  try {
    'foo'.localeCompare('bar', 'i');
  } catch (e) {
    return e.name === 'RangeError';
  }
  return false;
}

使用 `locales 参数`

在不同的语言下 localeCompare() 所提供的结果是不一致的。为了能让用户得到正确的比较值，通过使用 locales 参数来提供要比较的语言 (and possibly some fallback languages) :

console.log('ä'.localeCompare('z', 'de')); // a negative value: in German, ä sorts with a
console.log('ä'.localeCompare('z', 'sv')); // a positive value: in Swedish, ä sorts after z

使用 `options 参数`

localeCompare() 所提供的结果可以通过 options 参数来制定:

// in German, ä has a as the base letter
console.log('ä'.localeCompare('a', 'de', { sensitivity: 'base' })); // 0

// in Swedish, ä and a are separate base letters
console.log('ä'.localeCompare('a', 'sv', { sensitivity: 'base' })); // a positive value

性能相关

当比较大量字符串时，比如比较大量数组时，最好创建一个Intl.Collator 对象并使用compare 属性所提供的函数。

规范

规范	状态	说明
ECMAScript 3rd Edition (ECMA-262)	Standard	Initial definition. Implemented in JavaScript 1.2.
ECMAScript 5.1 (ECMA-262) String.prototype.localeCompare	Standard
ECMAScript 2015 (6th Edition, ECMA-262) String.prototype.localeCompare	Standard
ECMAScript Internationalization API 1.0 (ECMA-402) String.prototype.localeCompare	Standard	`locale` and `option` parameter definitions.

Feature	Chrome	Firefox (Gecko)	Internet Explorer	Opera	Safari
Basic support	(Yes)	(Yes)	(Yes)	(Yes)	(Yes)
`locales` and `options` arguments	24	29 (29)	11	15	未实现

Feature	Android	Chrome for Android	Firefox Mobile (Gecko)	IE Mobile	Opera Mobile	Safari Mobile
Basic support	(Yes)	(Yes)	(Yes)	(Yes)	(Yes)	(Yes)
`locales` and `options` arguments	未实现	26	未实现	未实现	未实现	未实现

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此页面的贡献者： helloguangxue, Ende93

最后编辑者: helloguangxue, Mar 1, 2016, 4:06:01 PM

另见

String.prototype.localeCompare()

语法

参数

描述

示例

使用 localeCompare()