JavaScript constants | Style and keyword

Question

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Are there constants in Javascript?

For example here I set the close time on this menu to 1 second or 1000 milliseconds.

menu.menu_timer=window.setTimeout(menu.hide_menu, 1000);

Does javascript have a const like C or a Define like PHP to define Constants?

Related, possible duplicate: http://stackoverflow.com/q/130396/497356 — Andrew Whitaker, Nov 16 '11 at 02:38

score 11 · Accepted Answer · edited Mar 12 '19 at 13:53

11

Update 2017

ES6, or ECMAScript2017, comes with the support for constants using the keyword const.

While some use camelCase syntax for the constant's names, it still is perfectly valid to use the capitalized (snake_case) version (e.g. const VARIABLE_NAME;)

Original answer

JavaScript does not have constants.

You could use the convention of all uppercase for constants.

var PI = 3.14;

or you could wrap it in an object.

window.CONSTANTS = {
   PI : 3.14
};

edited Mar 12 '19 at 13:53

answered Nov 16 '11 at 02:38

Daniel A. White

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its better to explain your scope. – Daniel A. White Nov 16 '11 at 02:48
Since ECMA script 6 you can use 'const' to define constants. – Adrian Lopez Jun 14 '16 at 04:31

score 4 · Answer 2 · answered Nov 16 '11 at 02:42

4

The standard convention for constants in JavaScript is to use all uppercase like

var MY_CONST = 1000;

There is a const keyword but I believe it is not supported in IE

answered Nov 16 '11 at 02:42

pradeek

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1

`const` is supported in IE 11+ – rink.attendant.6 Jan 05 '16 at 01:21

JavaScript constants | Style and keyword

2 Answers2

Update 2017

Original answer