should be
done instantly, otherwise the result might be unexpected.

##  Specifications

Specification  
---  
[ Legacy RegExp features  
#  additional-properties-of-the-regexp-constructor
](https://github.com/tc39/proposal-regexp-legacy-features/#additional-
properties-of-the-regexp-constructor)  
  
##  Browser compatibility

BCD tables only load in the browser  with JavaScript enabled. Enable
JavaScript to view data.

##  See also

  * [ ` RegExp.input ($_) ` ](/en-US/docs/Web/JavaScript/Reference/Global_Objects/RegExp/input)
  * [ ` RegExp.lastMatch ($&) ` ](/en-US/docs/Web/JavaScript/Reference/Global_Objects/RegExp/lastMatch)
  * [ ` RegExp.lastParen ($+) ` ](/en-US/docs/Web/JavaScript/Reference/Global_Objects/RegExp/lastParen)
  * [ ` RegExp.leftContext ($`) ` ](/en-US/docs/Web/JavaScript/Reference/Global_Objects/RegExp/leftContext)
  * [ ` RegExp.rightContext ($') ` ](/en-US/docs/Web/JavaScript/Reference/Global_Objects/RegExp/rightContext)

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