JavaScript applications consist of statements with an appropriate syntax. A single statement may span multiple lines. Multiple statements may occur on a single line if each statement is separated by a semicolon. This isn't a keyword, but a group of keywords.
Statements and declarations by category
For an alphabetical listing see the sidebar on the left.
Terminates execution of the statements in the current iteration of the current or labeled loop, and continues execution of the loop with the next iteration.
Creates a loop that executes a specified statement until the test condition evaluates to false. The condition is evaluated after executing the statement, resulting in the specified statement executing at least once.
Creates a loop that consists of three optional expressions, enclosed in parentheses and separated by semicolons, followed by a statement executed in the loop.
Iterates over iterable objects (including arrays, array-like objects, iterators and generators), invoking a custom iteration hook with statements to be executed for the value of each distinct property.
Iterates over async iterable objects, array-like objects, iterators and generators, invoking a custom iteration hook with statements to be executed for the value of each distinct property.
Creates a loop that executes a specified statement as long as the test condition evaluates to true. The condition is evaluated before executing the statement.
The compatibility table on this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.
Disabled From version 15: this feature is behind the Experimental JavaScript Features preference.
FirefoxFull support
60
Full support
60
No support
54 — 60
Disabled
Disabled From version 54 until version 60 (exclusive): this feature is behind the dom.moduleScripts.enabled preference. To change preferences in Firefox, visit about:config.
IENo support
No
OperaFull support
47
SafariFull support
10.1
WebView AndroidNo support
No
Chrome AndroidFull support
61
Firefox AndroidFull support
60
Full support
60
No support
54 — 60
Disabled
Disabled From version 54 until version 60 (exclusive): this feature is behind the dom.moduleScripts.enabled preference. To change preferences in Firefox, visit about:config.
Disabled From version 15: this feature is behind the Experimental JavaScript Features preference.
FirefoxFull support
60
Full support
60
No support
54 — 60
Disabled
Disabled From version 54 until version 60 (exclusive): this feature is behind the dom.moduleScripts.enabled preference. To change preferences in Firefox, visit about:config.
IENo support
No
OperaFull support
47
SafariFull support
10.1
WebView AndroidFull support
61
Chrome AndroidFull support
61
Firefox AndroidFull support
60
Full support
60
No support
54 — 60
Disabled
Disabled From version 54 until version 60 (exclusive): this feature is behind the dom.moduleScripts.enabled preference. To change preferences in Firefox, visit about:config.
Disabled From version 48 until version 49 (exclusive): this feature is behind the Enable Experimental JavaScript Features preference. To change preferences in Chrome, visit chrome://flags.
Notes 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.
FirefoxFull support
44
Notes
Full support
44
Notes
Notes Prior to 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).
Notes Prior to Firefox 46, a TypeError is thrown on redeclaration instead of a SyntaxError.
Notes Firefox 54 adds support of let in workers.
IEPartial support
11
Notes
Partial support
11
Notes
Notes 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.
Disabled From version 48 until version 49 (exclusive): this feature is behind the Enable Experimental JavaScript Features preference. To change preferences in Chrome, visit chrome://flags.
Notes Prior to 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).
Notes Prior to Firefox 46, a TypeError is thrown on redeclaration instead of a SyntaxError.
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1
1Which browsers are affected?
Please select the browser or browsers which are affected.
Chrome
Edge
Firefox
Internet Explorer
Opera
Safari
Android webview
Chrome for Android
Firefox for Android
Opera for Android
Safari on iOS
Samsung Internet
Node.js
2
2Which table row is affected?
3
3Can you provide a brief explanation?
Briefly outline the issue you are highlighting.
4
4Do you have any supporting material?Optional
Browser documentation and release notes are good supporting items to accompany your message. A demo hosted on services like Codepen or JSBin are perfect for providing real examples of your findings.
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