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This article mainly introduces the meaning of constant in JavaScript. It is very detailed and has a certain reference value. Friends who are interested must read it!

In JavaScript, a constant is an immutable quantity, which is usually used to store data that is neither changed nor desired; the value of the constant remains unchanged throughout the running of the script code and cannot be re-modified.

The operating environment of this tutorial: windows7 system, javascript1.8.5 version, Dell G3 computer.

Variables declared using var and let can be changed while the script code is running. If you want the value of the variable to remain the same throughout the run of the script code, you need to use const to declare it, and once defined, it cannot be modified (that is, constant defined using the const keyword).

The format of the declaration is as follows:

Const variable name = value

The so-called constant is a quantity that cannot be changed. It is usually used to store data that is neither changed nor desired. Once defined, it cannot be modified.

Constants, like variables, are containers for storing data, except that the value of the constant cannot be changed while the program is running, otherwise an error will be reported at run time.

Const a = 1 / / when the constant an is created, when an is assigned again, an is still 1console.log (a); a = 10 console.log (a) / / error report

Classification of constants

1. Integer constant

An integer constant is actually a positive number, and any integer written in JavaScript is an integer constant.

2. Real constant

Real constants are decimals.

3. String constant

A string constant is actually something enclosed in single or double quotation marks, which we call a string constant.

4. Boolean constant

Boolean constants are actually true or false, expressed by true and false in JavaScript

Boolean constants have only two values in JavaScript, true (true) or false (false)

The above is all the content of this article "what does constant in JavaScript mean?" Thank you for reading! Hope to share the content to help you, more related knowledge, welcome to follow the industry information channel!

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