On the standards track: Yes
Is Experimental: No
Is Deprecated: No
In Bun version 1.0.0 on 2023-09-08
In Chrome version 49 on 2016-03-02 Note: Strict mode is required.
In Chrome Android version 49 on 2016-03-09 Note: Strict mode is required.
In Deno version 1.0 on 2020-05-13
In Edge version 14 on 2016-08-02 Note: In Edge 12 and 13, let within a for loop initializer does not create a separate variable for each loop iteration as defined by ES2015. Instead, it behaves as though the loop were wrapped in a scoping block with the let immediately before the loop.
In Firefox version 44 on 2016-01-26 Note: Before Firefox 44, let is only available to code blocks in HTML wrapped in a <script type="application/javascript;version=1.7"> block (or higher version) and has different semantics (e.g. no temporal dead zone). Before Firefox 46, a TypeError is thrown on redeclaration instead of a SyntaxError. Firefox 54 adds support of let in workers.
In Firefox for Android version 44 on 2016-01-26 Note: Before Firefox for Android 44, let is only available to code blocks in HTML wrapped in a <script type="application/javascript;version=1.7"> block (or higher version) and has different semantics (e.g. no temporal dead zone). Before Firefox for Android 46, a TypeError is thrown on redeclaration instead of a SyntaxError. Firefox for Android 54 adds support of let in workers.
In Internet Explorer version 11 on 2013-10-17 Note: In Internet Explorer, let within a for loop initializer does not create a separate variable for each loop iteration as defined by ES2015. Instead, it behaves as though the loop were wrapped in a scoping block with the let immediately before the loop.
In Node.js version 6.0.0 on 2016-04-26
In Quest Browser version 5.0 on undefined
In Opera version 17 on 2013-10-08
In Opera Android version 18 on 2013-11-20
In Safari version 10 on 2016-09-20
In Safari on iOS version 10 on 2016-09-13
In Samsung Internet version 5.0 on 2016-12-15 Note: Strict mode is required.
In WebView Android version 49 on 2016-03-09 Note: Strict mode is required.
In WebView on iOS version 10 on 2016-09-13