RegExp.leftContext ($`)

Deprecated

Avoid using this feature in new projects. The RegExp static properties may have unintended side effects. This feature may be a candidate for removal from web standards or browsers.

: RegExp RegExp

RegExp.leftContext RegExp["$`"]

leftContext RegExp RegExp RegExp.leftContext RegExp["$`"]

leftContext RegExp RegExp leftContext leftContext undefined

(RegExp.$` ) ` SyntaxError

$` String.prototype.replace() RegExp["$`"]

leftContext $`

const re = /world/g;
re.test("hello world!");
RegExp.leftContext; // "hello "
RegExp["$`"]; // "hello "


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

RegExp.input ($_)
RegExp.lastMatch ($&)
RegExp.lastParen ($+)
RegExp.rightContext ($')
RegExp.$1, , RegExp.$9

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MDN 20251110

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RegExp
1. RegExp()
1. escape()
Object/Function
1. __proto__
2. constructor