const

Read More at MDN DocsView Spec

Safe to Use

const is considered safe to use.

It’s supported by 94% of global browsers.

Browsers

ChromeJul 31, 2012v21.0.0
26%╱100%
100% of Chrome users are running a supported version.
SafariJul 20, 2011v5.1.0
5%╱100%
100% of Safari users are running a supported version.
EdgeJul 28, 2015v12.0.0
5%╱100%
100% of Edge users are running a supported version.
FirefoxFeb 24, 2015v36.0.0
3%╱100%
100% of Firefox users are running a supported version.

Servers

Node.jsApr 26, 2016v6.0.0
Node.js supports this feature.
DenoMay 4, 2020v1.0.0
Deno supports this feature.

Version Breakdown

 
Agent
Support
Adoption
Chrome
Jul 31, 2012 v21.0.0
26%╱100%
100% of Chrome users are running a supported version.
Jul 31, 2012 – Latest
v21.0.0+
26%╱100%

Full Support

Chrome Android
Feb 27, 2013 v25.0.0
36%╱100%
100% of Chrome Android users are running a supported version.
Feb 27, 2013 – Latest
v25.0.0+
36%╱100%

Full Support

Deno
May 4, 2020 v1.0.0
Deno supports this feature.
May 4, 2020 – Latest
v1.0.0+

Full Support

Edge
Jul 28, 2015 v12.0.0
5%╱100%
100% of Edge users are running a supported version.
Jul 28, 2015 – Latest
v12.0.0+
5%╱100%

Full Support

Firefox
Feb 24, 2015 v36.0.0
3%╱100%
100% of Firefox users are running a supported version.
Feb 24, 2015 – Latest
v36.0.0+
3%╱100%

Full Support

Before Firefox 13, const is implemented, but re-assignment is not failing.

Before Firefox 46, a TypeError was thrown on redeclaration instead of a SyntaxError.

Firefox for Android
Feb 27, 2015 v36.0.0
Firefox for Android supports this feature.
Feb 27, 2015 – Latest
v36.0.0+

Full Support

Before Firefox 13, const is implemented, but re-assignment is not failing.

Before Firefox 46, a TypeError was thrown on redeclaration instead of a SyntaxError.

Internet Explorer
Oct 17, 2013 v11.0.0
0%╱83%
There are no users of Internet Explorer running a supported version.
Oct 17, 2013 – Latest
v11.0.0+
0%╱83%

Full Support

Node.js
Apr 26, 2016 v6.0.0
Node.js supports this feature.
Apr 26, 2016 – Latest
v6.0.0+

Full Support

 
Quest Browser
Unknown v5.0.0
Quest Browser supports this feature.
Unknown
v5.0.0+

Full Support

Opera
Jun 20, 2006 v9.0.0
1%╱100%
100% of Opera users are running a supported version.
Jun 20, 2006 – Latest
v9.0.0+
1%╱100%

Full Support

Opera Android
Nov 9, 2010 v10.1.0
Opera Android supports this feature.
Nov 9, 2010 – Latest
v10.1.0+

Full Support

Safari
Jul 20, 2011 v5.1.0
5%╱100%
100% of Safari users are running a supported version.
Jul 20, 2011 – Latest
v5.1.0+
5%╱100%

Full Support

Safari on iOS
Oct 12, 2011 v5.0.0
17%╱100%
There are no users of Safari on iOS running a supported version.
Oct 12, 2011 – Latest
v5.0.0+
17%╱100%

Full Support

Samsung Internet
Sep 25, 2013 v1.5.0
2%╱100%
100% of Samsung Internet users are running a supported version.
Sep 25, 2013 – Latest
v1.5.0+
2%╱100%

Full Support

WebView Android
Dec 9, 2013 v4.4.0
WebView Android supports this feature.
Dec 9, 2013 – Latest
v4.4.0+

Full Support

See Also

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