RegExp.lastParen ($+)

Deprecated: This feature is no longer recommended. Though some browsers might still support it, it may have already been removed from the relevant web standards, may be in the process of being dropped, or may only be kept for compatibility purposes. Avoid using it, and update existing code if possible; see the compatibility table at the bottom of this page to guide your decision. Be aware that this feature may cease to work at any time.

注意：所有全局公开最后匹配状态的 RegExp 静态属性均已弃用。请参阅 已弃用的 RegExp 功能 了解更多信息。

¥Note: All RegExp static properties that expose the last match state globally are deprecated. See deprecated RegExp features for more information.

RegExp.lastParen 静态访问器属性返回最后一个带括号的子字符串匹配项（如果有）。RegExp["$+"] 是该属性的别名。

¥The RegExp.lastParen static accessor property returns the last parenthesized substring match, if any. RegExp["$+"] is an alias for this property.

描述

¥Description

由于 lastParen 是 RegExp 的静态属性，因此你始终将其用作 RegExp.lastParen 或 RegExp["$+"]，而不是用作你创建的 RegExp 对象的属性。

¥Because lastParen is a static property of RegExp, you always use it as RegExp.lastParen or RegExp["$+"], rather than as a property of a RegExp object you created.

每当 RegExp（但不是 RegExp 子类）实例成功匹配时，lastParen 的值就会更新。如果未进行任何匹配，或者最近的正则表达式执行不包含捕获组，则 lastParen 为空字符串。lastParen 的 set 访问器是 undefined，因此你不能直接更改此属性。

¥The value of lastParen updates whenever a RegExp (but not a RegExp subclass) instance makes a successful match. If no matches have been made, or if the most recent regex execution contains no capturing groups, lastParen is an empty string. The set accessor of lastParen is undefined, so you cannot change this property directly.

你不能将简写别名与点属性访问器 (RegExp.$+) 一起使用，因为 + 不是有效的标识符部分，因此这会导致 SyntaxError。请改用 括号表示法。

¥You cannot use the shorthand alias with the dot property accessor (RegExp.$+), because + is not a valid identifier part, so this causes a SyntaxError. Use the bracket notation instead.

示例

¥Examples

使用 lastParen 和$+

¥Using lastParen and $+

js
const re = /(hi)/g;
re.test("hi there!");
RegExp.lastParen; // "hi"
RegExp["$+"]; // "hi"

规范

Specification
Legacy RegExp features
# additional-properties-of-the-regexp-constructor

¥Specifications

浏览器兼容性

BCD tables only load in the browser

¥Browser compatibility

也可以看看

¥See also