What meaning of &= in JavaScript

Question

I see the below code inside GoogleChrome/puppeteer:

    this._modifiers &= ~this._modifierBit(description.key);

you can find in this file: code.

And my question is why use &=, and how it works?

All you need to know is in https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Bitwise_Operators Hard to hammer close as dupe though because you asked for multiple operators, but for `&` this [Q/A](https://stackoverflow.com/questions/47802087/what-mathematical-function-does-bitwise-and-operator-do-js/47802203), for `~` [this one](https://stackoverflow.com/questions/4295578/explanation-of-bitwise-not-operator) — Kaiido, Sep 17 '18 at 08:17

Ankit Agarwal · Answer 1 · 2018-09-17T08:09:51.070

1

this._modifiers &= ~this._modifierBit(description.key); is a short hand of

this._modifiers = this._modifiers & ~this._modifierBit(description.key);

It depends on the coding style you opt to chose as both of them have same complexity based on computation. That is just a shorthand feature supported by the programming language. Some more examples are:

a += 10 equivalent to a = a+10
a *= 10 equivalent to a = a*10

edited Sep 17 '18 at 08:09

answered Sep 17 '18 at 08:07

Ankit Agarwal

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and what is the `~this` means? – Saeed Jalali Sep 17 '18 at 08:09
~this is the bitwise negation (inversion) of this. This is just a common pattern to reset a value, depending on some specific bits (bit mask). – elasticman Sep 17 '18 at 08:22

What meaning of &= in JavaScript

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