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• 描述
• 构造函数
• 静态方法
• 实例特性
• 实例方法
• HTML 包裹器方法
• 范例
• 规范
• 浏览器兼容性
• 另请参阅
• 相关话题

String 对象用于表示和操纵字符序列。

描述

字符串对于可以以文本形式表示保持的数据是有用的。最常用的一些字符串操作是校验其 length ，要构建和串联它们使用 + 和 += 字符串运算符 ，检查子字符串的存在或位置采用 indexOf() 方法，或提取子字符串采用 substring() 方法。

创建字符串

可以把字符串创建作为原语，从字符串文字或作为对象，使用 String() 构造函数：

const string1 = "A string primitive";
const string2 = 'Also a string primitive';
const string3 = `Yet another string primitive`;
					

const string4 = new String("A String object");
					

String primitives and string objects can be used interchangeably in most situations. See " 字符串原语和字符串对象 " below.

String literals can be specified using single or double quotes, which are treated identically, or using the backtick character ` . This last form specifies a template literal : with this form you can interpolate expressions.

字符访问

There are two ways to access an individual character in a string. The first is the charAt() method:

return 'cat'.charAt(1) // returns "a"
					

The other way (introduced in ECMAScript 5) is to treat the string as an array-like object, where individual characters correspond to a numerical index:

return 'cat'[1] // returns "a"
					

When using bracket notation for character access, attempting to delete or assign a value to these properties will not succeed. The properties involved are neither writable nor configurable. (See Object.defineProperty() for more information.)

比较字符串

In C, the strcmp() function is used for comparing strings. In JavaScript, you just use the less-than and greater-than operators :

let a = 'a'
let b = 'b'
if (a < b) { // true
  console.log(a + ' is less than ' + b)
} else if (a > b) {
  console.log(a + ' is greater than ' + b)
} else {
  console.log(a + ' and ' + b + ' are equal.')
}
					

A similar result can be achieved using the localeCompare() method inherited by String 实例。

注意， a == b compares the strings in a and b for being equal in the usual case-sensitive way. If you wish to compare without regard to upper or lower case characters, use a function similar to this:

function isEqual(str1, str2)
{
    return str1.toUpperCase() === str2.toUpperCase()
} // isEqual
					

Upper case is used instead of lower case in this function, due to problems with certain UTF-8 character conversions.

字符串原语和字符串对象

注意，JavaScript 区分 String 对象和 原语字符串 值。(如同 true 的 布尔 and 数字 .)

String literals (denoted by double or single quotes) and strings returned from String calls in a non-constructor context (that is, called without using the new keyword) are primitive strings. JavaScript automatically converts primitives to String objects, so that it's possible to use String object methods for primitive strings. In contexts where a method is to be invoked on a primitive string or a property lookup occurs, JavaScript will automatically wrap the string primitive and call the method or perform the property lookup.

let s_prim = 'foo'
let s_obj = new String(s_prim)
console.log(typeof s_prim) // Logs "string"
console.log(typeof s_obj)  // Logs "object"
					

字符串原语和 String objects also give different results when using eval() . Primitives passed to eval are treated as source code; String objects are treated as all other objects are, by returning the object. For example:

let s1 = '2 + 2'              // creates a string primitive
let s2 = new String('2 + 2')  // creates a String object
console.log(eval(s1))         // returns the number 4
console.log(eval(s2))         // returns the string "2 + 2"
					

For these reasons, the code may break when it encounters String objects when it expects a primitive string instead, although generally, authors need not worry about the distinction.

A String object can always be converted to its primitive counterpart with the valueOf() 方法。

console.log(eval(s2.valueOf()))  // returns the number 4
					

转义表示法

可以使用转义表示法编码特殊字符：

代码	输出
\ XXX (where XXX is 1–3 octal digits; range of 0 – 377 )	ISO-8859-1 character / Unicode code point between U+0000 and U+00FF
\'	单引号
\"	双引号
\\	backslash
\n	换行
\r	CR (回车)
\v	vertical tab
\t	tab
\b	backspace
\f	换页
\u XXXX (where XXXX is 4 hex digits; range of 0x0000 – 0xFFFF )	UTF-16 code unit / Unicode code point between U+0000 and U+FFFF
\u{ X } ... \u{ XXXXXX } (where X … XXXXXX is 1–6 hex digits; range of 0x0 – 0x10FFFF )	UTF-32 code unit / Unicode code point between U+0000 and U+10FFFF
\x XX (where XX is 2 hex digits; range of 0x00 – 0xFF )	ISO-8859-1 character / Unicode code point between U+0000 and U+00FF

长文字字符串

Sometimes, your code will include strings which are very long. Rather than having lines that go on endlessly, or wrap at the whim of your editor, you may wish to specifically break the string into multiple lines in the source code without affecting the actual string contents. There are two ways you can do this.

方法 1

可以使用 + 运算符把多个字符串追加到一起，像这样：

let longString = "This is a very long string which needs " +
                 "to wrap across multiple lines because " +
                 "otherwise my code is unreadable."
					

方法 2

可以使用反斜杠字符 ( \ ) at the end of each line to indicate that the string will continue on the next line. Make sure there is no space or any other character after the backslash (except for a line break), or as an indent; otherwise it will not work.

That form looks like this:

let longString = "This is a very long string which needs \
to wrap across multiple lines because \
otherwise my code is unreadable."
					

Both of the above methods result in identical strings.

构造函数

String()

创建新的 String object. It performs type conversion when called as a function, rather than as a constructor, which is usually more useful.

静态方法

String.fromCharCode( num1 [, ...[, numN ]])

Returns a string created by using the specified sequence of Unicode values.

String.fromCodePoint( num1 [, ...[, numN )

Returns a string created by using the specified sequence of code points.

String.raw()

Returns a string created from a raw template string.

实例特性

String.prototype.length

反射 length 对于字符串。只读。

实例方法

String.prototype.charAt( index )

Returns the character (exactly one UTF-16 code unit) at the specified index .

String.prototype.charCodeAt( index )

Returns a number that is the UTF-16 code unit value at the given index .

String.prototype.codePointAt( pos )

Returns a nonnegative integer Number that is the code point value of the UTF-16 encoded code point starting at the specified pos .

String.prototype.concat( str [, ... strN ])

Combines the text of two (or more) strings and returns a new string.

String.prototype.includes( searchString [, position ])

Determines whether the calling string contains searchString .

String.prototype.endsWith( searchString [, length ])

Determines whether a string ends with the characters of the string searchString .

String.prototype.indexOf( searchValue [, fromIndex ])

Returns the index within the calling String object of the first occurrence of searchValue ，或 -1 若找不到。

String.prototype.lastIndexOf( searchValue [, fromIndex ])

Returns the index within the calling String object of the last occurrence of searchValue ，或 -1 若找不到。

String.prototype.localeCompare( compareString [, locales [, options ]])

Returns a number indicating whether the reference string compareString comes before, after, or is equivalent to the given string in sort order.

String.prototype.match( regexp )

Used to match regular expression regexp 与字符串。

String.prototype.matchAll( regexp )

Returns an iterator of all regexp 's matches.

String.prototype.normalize([ form ])

Returns the Unicode Normalization Form of the calling string value.

String.prototype.padEnd( targetLength [, padString ])

Pads the current string from the end with a given string and returns a new string of the length targetLength .

String.prototype.padStart( targetLength [, padString ])

Pads the current string from the start with a given string and returns a new string of the length targetLength .

String.prototype.repeat( count )

Returns a string consisting of the elements of the object repeated count times.

String.prototype.replace( searchFor , replaceWith )

Used to replace occurrences of searchFor 使用 replaceWith . searchFor may be a string or Regular Expression, and replaceWith 可以是字符串 (或函数)。

String.prototype.replaceAll( searchFor , replaceWith )

Used to replace all occurrences of searchFor 使用 replaceWith . searchFor may be a string or Regular Expression, and replaceWith 可以是字符串 (或函数)。

String.prototype.search( regexp )

Search for a match between a regular expression regexp and the calling string.

String.prototype.slice( beginIndex [, endIndex ])

Extracts a section of a string and returns a new string.

String.prototype.split([ sep [, limit ] ])

Returns an array of strings populated by splitting the calling string at occurences of the substring sep .

String.prototype.startsWith( searchString [, length ])

Determines whether the calling string begins with the characters of string searchString .

String.prototype.substr()

返回从指定位置开始到指定字符数的字符串中的字符。

String.prototype.substring( indexStart [, indexEnd ])

Returns a new string containing characters of the calling string from (or between) the specified index (or indeces).

String.prototype.toLocaleLowerCase( [ locale , ... locales ])

The characters within a string are converted to lowercase while respecting the current locale.

For most languages, this will return the same as toLowerCase() .

String.prototype.toLocaleUpperCase( [ locale , ... locales ])

The characters within a string are converted to uppercase while respecting the current locale.

For most languages, this will return the same as toUpperCase() .

String.prototype.toLowerCase()

Returns the calling string value converted to lowercase.

String.prototype.toString()

Returns a string representing the specified object. Overrides the Object.prototype.toString() 方法。

String.prototype.toUpperCase()

返回被转换为大写的调用字符串值。

String.prototype.trim()

Trims whitespace from the beginning and end of the string. Part of the ECMAScript 5 standard.

String.prototype.trimStart()

Trims whitespace from the beginning of the string.

String.prototype.trimEnd()

从字符串末尾开始修剪空白。

String.prototype.valueOf()

Returns the primitive value of the specified object. Overrides the Object.prototype.valueOf() 方法。

String.prototype.@@iterator()

返回新的 Iterator object that iterates over the code points of a String value, returning each code point as a String value.

HTML 包裹器方法

弃用。避免这些方法。

它们用途有限，因为它们仅提供可用 HTML 标签和属性的子集。

String.prototype.anchor()

<a name="name"> (超文本目标)

String.prototype.big()

<big>

String.prototype.blink()

<blink>

String.prototype.bold()

<b>

String.prototype.fixed()

<tt>

String.prototype.fontcolor()

<font color="color">

String.prototype.fontsize()

<font size="size">

String.prototype.italics()

<i>

String.prototype.link()

<a href="url"> (链接到 URL)

String.prototype.small()

<small>

String.prototype.strike()

<strike>

String.prototype.sub()

<sub>

String.prototype.sup()

<sup>

范例

字符串转换

它是可能的使用 String 作为更可靠的 toString() alternative, as it works when used on null , undefined , and on symbols 。例如：

let outputStrings = []
for (let i = 0, n = inputValues.length; i < n; ++i) {
  outputStrings.push(String(inputValues[i]));
}
					

规范

规范
ECMAScript (ECMA-262) 在该规范中的 String 定义。

浏览器兼容性

The compatibility table in this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request. 更新 GitHub 上的兼容性数据

	Desktop						Mobile						Server
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet	Node.js
String	Chrome 1	Edge 12	Firefox 1	IE 3	Opera 3	Safari 1	WebView Android 1	Chrome Android 18	Firefox Android 4	Opera Android 10.1	Safari iOS 1	Samsung Internet Android 1.0	nodejs 0.1.100
String() 构造函数	Chrome 1	Edge 12	Firefox 1	IE 3	Opera 3	Safari 1	WebView Android 1	Chrome Android 18	Firefox Android 4	Opera Android 10.1	Safari iOS 1	Samsung Internet Android 1.0	nodejs 0.1.100
anchor 弃用	Chrome 1	Edge 12	Firefox 1 1 Starting with version 17, the quotation mark (") is replaced by its HTML reference character ( " ) in strings supplied for the name 参数。	IE No	Opera 3	Safari 1	WebView Android 1	Chrome Android 18	Firefox Android 4	Opera Android 10.1	Safari iOS 1	Samsung Internet Android 1.0	nodejs 0.1.100
big 弃用	Chrome 1	Edge 12	Firefox 1	IE 3	Opera 3	Safari 1	WebView Android 1	Chrome Android 18	Firefox Android 4	Opera Android 10.1	Safari iOS 1	Samsung Internet Android 1.0	nodejs 0.1.100
blink 弃用	Chrome 1	Edge 12	Firefox 1	IE 3	Opera 3	Safari 1	WebView Android 1	Chrome Android 18	Firefox Android 4	Opera Android 10.1	Safari iOS 1	Samsung Internet Android 1.0	nodejs 0.1.100
bold 弃用	Chrome 1	Edge 12	Firefox 1	IE 3	Opera 3	Safari 1	WebView Android 1	Chrome Android 18	Firefox Android 4	Opera Android 10.1	Safari iOS 1	Samsung Internet Android 1.0	nodejs 0.1.100
charAt	Chrome 1	Edge 12	Firefox 1	IE 3	Opera 3	Safari 1	WebView Android 1	Chrome Android 18	Firefox Android 4	Opera Android 10.1	Safari iOS 1	Samsung Internet Android 1.0	nodejs 0.1.100
charCodeAt	Chrome 1	Edge 12	Firefox 1	IE 4	Opera 4	Safari 1	WebView Android 1	Chrome Android 18	Firefox Android 4	Opera Android 10.1	Safari iOS 1	Samsung Internet Android 1.0	nodejs 0.1.100
codePointAt	Chrome 41	Edge 12	Firefox 29	IE No	Opera 28	Safari 10	WebView Android 41	Chrome Android 41	Firefox Android 29	Opera Android 28	Safari iOS 10	Samsung Internet Android 4.0	nodejs 4.0.0 4.0.0 0.12 Disabled Disabled From version 0.12: this feature is behind the --harmony runtime flag.
concat	Chrome 1	Edge 12	Firefox 1	IE 4	Opera 4	Safari 1	WebView Android 1	Chrome Android 18	Firefox Android 4	Opera Android 10.1	Safari iOS 1	Samsung Internet Android 1.0	nodejs 0.1.100
endsWith	Chrome 41	Edge 12	Firefox 17	IE No	Opera 28	Safari 9	WebView Android ≤37	Chrome Android 36	Firefox Android 17	Opera Android 24	Safari iOS 9	Samsung Internet Android 3.0	nodejs 4.0.0 4.0.0 0.12 Disabled Disabled From version 0.12: this feature is behind the --harmony runtime flag.
fixed 弃用	Chrome 1	Edge 12	Firefox 1	IE 3	Opera 3	Safari 1	WebView Android 1	Chrome Android 18	Firefox Android 4	Opera Android 10.1	Safari iOS 1	Samsung Internet Android 1.0	nodejs 0.1.100
fontcolor 弃用	Chrome 1	Edge 12	Firefox 1	IE 3	Opera 3	Safari 1	WebView Android 1	Chrome Android 18	Firefox Android 4	Opera Android 10.1	Safari iOS 1	Samsung Internet Android 1.0	nodejs 0.1.100
fontsize 弃用	Chrome 1	Edge 12	Firefox 1	IE 3	Opera 3	Safari 1	WebView Android 1	Chrome Android 18	Firefox Android 4	Opera Android 10.1	Safari iOS 1	Samsung Internet Android 1.0	nodejs 0.1.100
fromCharCode	Chrome 1	Edge 12	Firefox 1	IE 4	Opera 4	Safari 1	WebView Android 1	Chrome Android 18	Firefox Android 4	Opera Android 10.1	Safari iOS 1	Samsung Internet Android 1.0	nodejs 0.1.100
fromCodePoint	Chrome 41	Edge 12	Firefox 29	IE No	Opera 28	Safari 10	WebView Android 41	Chrome Android 41	Firefox Android 29	Opera Android 28	Safari iOS 10	Samsung Internet Android 4.0	nodejs 4.0.0 4.0.0 0.12 Disabled Disabled From version 0.12: this feature is behind the --harmony runtime flag.
includes	Chrome 41	Edge 12	Firefox 40 40 不支持 18 — 48 Alternate Name Alternate Name Uses the non-standard name: contains	IE No	Opera 28	Safari 9	WebView Android 41	Chrome Android 41	Firefox Android 40 40 不支持 18 — 48 Alternate Name Alternate Name Uses the non-standard name: contains	Opera Android 28	Safari iOS 9	Samsung Internet Android 4.0	nodejs 4.0.0
indexOf	Chrome 1	Edge 12	Firefox 1	IE 3	Opera 3	Safari 1	WebView Android 1	Chrome Android 18	Firefox Android 4	Opera Android 10.1	Safari iOS 1	Samsung Internet Android 1.0	nodejs 0.1.100
italics 弃用	Chrome 1	Edge 12	Firefox 1	IE 3	Opera 3	Safari 1	WebView Android 1	Chrome Android 18	Firefox Android 4	Opera Android 10.1	Safari iOS 1	Samsung Internet Android 1.0	nodejs 0.1.100
lastIndexOf	Chrome 1	Edge 12	Firefox 1	IE 6	Opera 3	Safari 1	WebView Android 1	Chrome Android 18	Firefox Android 4	Opera Android 10.1	Safari iOS 1	Samsung Internet Android 1.0	nodejs 0.1.100
length	Chrome 1	Edge 12	Firefox 1	IE 3	Opera 3	Safari 1	WebView Android 1	Chrome Android 18	Firefox Android 4	Opera Android 10.1	Safari iOS 1	Samsung Internet Android 1.0	nodejs 0.1.100
link 弃用	Chrome 1	Edge 12	Firefox 1	IE 3	Opera 3	Safari 1	WebView Android 1	Chrome Android 18	Firefox Android 4	Opera Android 10.1	Safari iOS 1	Samsung Internet Android 1.0	nodejs 0.1.100
localeCompare	Chrome 1	Edge 12	Firefox 1	IE 5.5	Opera 7	Safari 3	WebView Android 1	Chrome Android 18	Firefox Android 4	Opera Android 10.1	Safari iOS 1	Samsung Internet Android 1.0	nodejs 0.1.100
match	Chrome 1	Edge 12	Firefox 1	IE 4	Opera 4	Safari 1	WebView Android 1	Chrome Android 18	Firefox Android 4	Opera Android 10.1	Safari iOS 1	Samsung Internet Android 1.0	nodejs 0.1.100
matchAll	Chrome 73	Edge 79	Firefox 67	IE No	Opera 60	Safari 13	WebView Android 73	Chrome Android 73	Firefox Android 67	Opera Android 52	Safari iOS 13	Samsung Internet Android No	nodejs 12.0.0
normalize	Chrome 34	Edge 12	Firefox 31	IE No	Opera 21	Safari 10	WebView Android No	Chrome Android 34	Firefox Android 31	Opera Android 21	Safari iOS 10	Samsung Internet Android 2.0	nodejs 0.12
padEnd	Chrome 57	Edge 15	Firefox 48	IE No	Opera 44	Safari 10	WebView Android 57	Chrome Android 57	Firefox Android 48	Opera Android 43	Safari iOS 10	Samsung Internet Android 7.0	nodejs 8.0.0 8.0.0 7.0.0 Disabled Disabled From version 7.0.0: this feature is behind the --harmony runtime flag.
padStart	Chrome 57	Edge 15	Firefox 48	IE No	Opera 44	Safari 10	WebView Android 57	Chrome Android 57	Firefox Android 48	Opera Android 43	Safari iOS 10	Samsung Internet Android 7.0	nodejs 8.0.0 8.0.0 7.0.0 Disabled Disabled From version 7.0.0: this feature is behind the --harmony runtime flag.
raw	Chrome 41	Edge 12	Firefox 34	IE No	Opera No	Safari 10	WebView Android No	Chrome Android 41	Firefox Android 34	Opera Android No	Safari iOS 10	Samsung Internet Android 4.0	nodejs 4.0.0
repeat	Chrome 41	Edge 12	Firefox 24	IE No	Opera 28	Safari 9	WebView Android No	Chrome Android 36	Firefox Android 24	Opera Android 28	Safari iOS 9	Samsung Internet Android 3.0	nodejs 4.0.0 4.0.0 0.12 Disabled Disabled From version 0.12: this feature is behind the --harmony runtime flag.
replace	Chrome 1	Edge 12	Firefox 1	IE 4	Opera 4	Safari 1	WebView Android 1	Chrome Android 18	Firefox Android 4	Opera Android 10.1	Safari iOS 1	Samsung Internet Android 1.0	nodejs 0.1.100
replaceAll	Chrome 85	Edge No	Firefox 77	IE No	Opera No	Safari 13.1	WebView Android 85	Chrome Android 85	Firefox Android No	Opera Android No	Safari iOS 13.4	Samsung Internet Android No	nodejs No
search	Chrome 1	Edge 12	Firefox 1	IE 4	Opera 4	Safari 1	WebView Android 1	Chrome Android 18	Firefox Android 4	Opera Android 10.1	Safari iOS 1	Samsung Internet Android 1.0	nodejs 0.1.100
slice	Chrome 1	Edge 12	Firefox 1	IE 4	Opera 4	Safari 1	WebView Android 1	Chrome Android 18	Firefox Android 4	Opera Android 10.1	Safari iOS 1	Samsung Internet Android 1.0	nodejs 0.1.100
small 弃用	Chrome 1	Edge 12	Firefox 1	IE 3	Opera 3	Safari 1	WebView Android 1	Chrome Android 18	Firefox Android 4	Opera Android 10.1	Safari iOS 1	Samsung Internet Android 1.0	nodejs 0.1.100
split	Chrome 1	Edge 12	Firefox 1	IE 4	Opera 3	Safari 1	WebView Android 1	Chrome Android 18	Firefox Android 4	Opera Android 10.1	Safari iOS 1	Samsung Internet Android 1.0	nodejs 0.1.100
startsWith	Chrome 41	Edge 12	Firefox 17	IE No	Opera 28	Safari 9	WebView Android ≤37	Chrome Android 36	Firefox Android 17	Opera Android 24	Safari iOS 9	Samsung Internet Android 3.0	nodejs 4.0.0 4.0.0 0.12 Disabled Disabled From version 0.12: this feature is behind the --harmony runtime flag.
strike 弃用	Chrome 1	Edge 12	Firefox 1	IE 3	Opera 3	Safari 1	WebView Android 1	Chrome Android 18	Firefox Android 4	Opera Android 10.1	Safari iOS 1	Samsung Internet Android 1.0	nodejs 0.1.100
sub 弃用	Chrome 1	Edge 12	Firefox 1	IE 3	Opera 3	Safari 1	WebView Android 1	Chrome Android 18	Firefox Android 4	Opera Android 10.1	Safari iOS 1	Samsung Internet Android 1.0	nodejs 0.1.100
substr 弃用	Chrome 1	Edge 12	Firefox 1	IE 4	Opera 4	Safari 1	WebView Android 1	Chrome Android 18	Firefox Android 4	Opera Android 10.1	Safari iOS 1	Samsung Internet Android 1.0	nodejs 0.1.100
substring	Chrome 1	Edge 12	Firefox 1	IE 3	Opera 3	Safari 1	WebView Android 1	Chrome Android 18	Firefox Android 4	Opera Android 10.1	Safari iOS 1	Samsung Internet Android 1.0	nodejs 0.1.100
sup 弃用	Chrome 1	Edge 12	Firefox 1	IE 3	Opera 3	Safari 1	WebView Android 1	Chrome Android 18	Firefox Android 4	Opera Android 10.1	Safari iOS 1	Samsung Internet Android 1.0	nodejs 0.1.100
toLocaleLowerCase	Chrome 1	Edge 12	Firefox 1	IE 5.5	Opera 4	Safari 1.3	WebView Android 1	Chrome Android 18	Firefox Android 4	Opera Android 10.1	Safari iOS 1	Samsung Internet Android 1.0	nodejs 0.1.100
toLocaleUpperCase	Chrome 1	Edge 12	Firefox 1	IE 5.5	Opera 4	Safari 1.3	WebView Android 1	Chrome Android 18	Firefox Android 4	Opera Android 10.1	Safari iOS 1	Samsung Internet Android 1.0	nodejs 0.1.100
toLowerCase	Chrome 1	Edge 12	Firefox 1	IE 3	Opera 3	Safari 1	WebView Android 1	Chrome Android 18	Firefox Android 4	Opera Android 10.1	Safari iOS 1	Samsung Internet Android 1.0	nodejs 0.1.100
toSource 非标	Chrome No	Edge No	Firefox 1 — 74 不支持 1 — 74 Starting in Firefox 74, toSource() is no longer available for use by web content. It is still allowed for internal and privileged code.	IE No	Opera No	Safari No	WebView Android No	Chrome Android No	Firefox Android 4	Opera Android No	Safari iOS No	Samsung Internet Android No	nodejs No
toString	Chrome 1	Edge 12	Firefox 1	IE 3	Opera 3	Safari 1	WebView Android 1	Chrome Android 18	Firefox Android 4	Opera Android 10.1	Safari iOS 1	Samsung Internet Android 1.0	nodejs 0.1.100
toUpperCase	Chrome 1	Edge 12	Firefox 1	IE 3	Opera 3	Safari 1	WebView Android 1	Chrome Android 18	Firefox Android 4	Opera Android 10.1	Safari iOS 1	Samsung Internet Android 1.0	nodejs 0.1.100
trim	Chrome 4	Edge 12	Firefox 3.5	IE 9	Opera 10.5	Safari 5	WebView Android ≤37	Chrome Android 18	Firefox Android 4	Opera Android 11	Safari iOS 5	Samsung Internet Android 1.0	nodejs 0.1.100
trimEnd	Chrome 66 66 4 Alternate Name Alternate Name Uses the non-standard name: trimRight	Edge 12 Alternate Name 12 Alternate Name Alternate Name Uses the non-standard name: trimRight	Firefox 61 61 3.5 Alternate Name Alternate Name Uses the non-standard name: trimRight	IE No	Opera 53 53 15 Alternate Name Alternate Name Uses the non-standard name: trimRight	Safari 12	WebView Android 66 66 ≤37 Alternate Name Alternate Name Uses the non-standard name: trimRight	Chrome Android 66 66 18 Alternate Name Alternate Name Uses the non-standard name: trimRight	Firefox Android 61 61 4 Alternate Name Alternate Name Uses the non-standard name: trimRight	Opera Android 47 47 14 Alternate Name Alternate Name Uses the non-standard name: trimRight	Safari iOS 12	Samsung Internet Android 9.0 9.0 1.0 Alternate Name Alternate Name Uses the non-standard name: trimRight	nodejs 10.0.0 10.0.0 0.12 Alternate Name Alternate Name Uses the non-standard name: trimRight
trimStart	Chrome 66 66 4 Alternate Name Alternate Name Uses the non-standard name: trimLeft	Edge 12 Alternate Name 12 Alternate Name Alternate Name Uses the non-standard name: trimLeft	Firefox 61 61 3.5 Alternate Name Alternate Name Uses the non-standard name: trimLeft	IE No	Opera 53 53 15 Alternate Name Alternate Name Uses the non-standard name: trimLeft	Safari 12	WebView Android 66 66 ≤37 Alternate Name Alternate Name Uses the non-standard name: trimLeft	Chrome Android 66 66 18 Alternate Name Alternate Name Uses the non-standard name: trimLeft	Firefox Android 61 61 4 Alternate Name Alternate Name Uses the non-standard name: trimLeft	Opera Android 47 47 14 Alternate Name Alternate Name Uses the non-standard name: trimLeft	Safari iOS 12	Samsung Internet Android 9.0 9.0 1.0 Alternate Name Alternate Name Uses the non-standard name: trimLeft	nodejs 10.0.0 10.0.0 0.12 Alternate Name Alternate Name Uses the non-standard name: trimLeft
Unicode code point escapes \u{xxxxxx}	Chrome 1	Edge 12	Firefox 40	IE 4	Opera 4	Safari 1	WebView Android 1	Chrome Android 18	Firefox Android 40	Opera Android 10.1	Safari iOS 1	Samsung Internet Android 1.0	nodejs 0.1.100
valueOf	Chrome 1	Edge 12	Firefox 1	IE 4	Opera 3	Safari 1	WebView Android 1	Chrome Android 18	Firefox Android 4	Opera Android 10.1	Safari iOS 1	Samsung Internet Android 1.0	nodejs 0.1.100
@@iterator	Chrome 38	Edge 12	Firefox 36 36 不支持 27 — 36 Alternate Name A placeholder property named @@iterator 被使用。 Alternate Name Uses the non-standard name: @@iterator 不支持 17 — 27 Alternate Name A placeholder property named iterator 被使用。 Alternate Name Uses the non-standard name: iterator	IE No	Opera 25	Safari No	WebView Android 38	Chrome Android 38	Firefox Android 36 36 不支持 27 — 36 Alternate Name A placeholder property named @@iterator 被使用。 Alternate Name Uses the non-standard name: @@iterator 不支持 17 — 27 Alternate Name A placeholder property named iterator 被使用。 Alternate Name Uses the non-standard name: iterator	Opera Android 25	Safari iOS No	Samsung Internet Android 3.0	nodejs 0.12

图例

完整支持

完整支持

不支持

不支持

非标。预期跨浏览器支持较差。

非标。预期跨浏览器支持较差。

弃用。不要用于新网站。

弃用。不要用于新网站。

见实现注意事项。

用户必须明确启用此特征。

用户必须明确启用此特征。

使用非标名称。

另请参阅

• JavaScript 指南中的文本格式化
• RegExp
• DOMString
• StringView — 基于类型化数组的像 C 的字符串表示
• 二进制字符串

元数据

• 最后修改： Aug 4, 2020

相关话题

1. 标准内置对象
2. String
3. 特性
   1. String 长度
4. 方法
   1. String.fromCharCode()
   2. String.fromCodePoint()
   3. String.prototype.anchor()
   4. String.prototype.big()
   5. String.prototype.blink()
   6. String.prototype.bold()
   7. String.prototype.charAt()
   8. String.prototype.charCodeAt()
   9. String.prototype.codePointAt()
   10. String.prototype.concat()
   11. String.prototype.endsWith()
   12. String.prototype.fixed()
   13. String.prototype.fontcolor()
   14. String.prototype.fontsize()
   15. String.prototype.includes()
   16. String.prototype.indexOf()
   17. String.prototype.italics()
   18. String.prototype.lastIndexOf()
   19. String.prototype.link()
   20. String.prototype.localeCompare()
   21. String.prototype.match()
   22. String.prototype.matchAll()
   23. String.prototype.normalize()
   24. String.prototype.padEnd()
   25. String.prototype.padStart()
   26. String.prototype.repeat()
   27. String.prototype.replace()
   28. String.prototype.replaceAll()
   29. String.prototype.search()
   30. String.prototype.slice()
   31. String.prototype.small()
   32. String.prototype.split()
   33. String.prototype.startsWith()
   34. String.prototype.strike()
   35. String.prototype.sub()
   36. String.prototype.substr()
   37. String.prototype.substring()
   38. String.prototype.sup()
   39. String.prototype.toLocaleLowerCase()
   40. String.prototype.toLocaleUpperCase()
   41. String.prototype.toLowerCase()
   42. String.prototype.toSource()
   43. String.prototype.toString()
   44. String.prototype.toUpperCase()
   45. String.prototype.trim()
   46. String.prototype.trimEnd()
   47. String.prototype.trimStart()
   48. String.prototype.valueOf()
   49. String.prototype[@@iterator]()
   50. String.raw()
5. 继承：
6. Function
7. 特性
   1. Function.arguments
   2. Function.caller
   3. Function.displayName
   4. Function.length
   5. Function.name
8. 方法
   1. Function.prototype.apply()
   2. Function.prototype.bind()
   3. Function.prototype.call()
   4. Function.prototype.toSource()
   5. Function.prototype.toString()
9. Object
10. 特性
    1. Object.prototype.__proto__
    2. Object.prototype.constructor
11. 方法
    1. Object.prototype.__defineGetter__()
    2. Object.prototype.__defineSetter__()
    3. Object.prototype.__lookupGetter__()
    4. Object.prototype.__lookupSetter__()
    5. Object.prototype.hasOwnProperty()
    6. Object.prototype.isPrototypeOf()
    7. Object.prototype.propertyIsEnumerable()
    8. Object.prototype.toLocaleString()
    9. Object.prototype.toSource()
    10. Object.prototype.toString()
    11. Object.prototype.valueOf()
    12. Object.setPrototypeOf()