What keywords are used to define variables in javascript?

In JavaScript, use the keywords let and const to define variables. let is used for mutable variables, allowing reassignment; const is used for constant variables, which cannot be changed once assigned.

Keywords for defining variables in JavaScript

In JavaScript, keywordslet and const are used to define variables.

let

• let keyword is used to define variable variables, which means that the value of the variable can be changed during the execution of the program. Redistribute.
• The let keyword was introduced in ES6 (2015 version) and is the preferred way to define variables.

const

• The const keyword is used to define constant variables, which means that once the value of the variable is initialized, It cannot be reassigned.
• The const keyword was also introduced starting with ES6 to ensure that the value of a variable does not change unexpectedly.

Example

// 使用 let 定义可变变量
let name = "John";
name = "Doe"; // 允许重新分配

// 使用 const 定义常量变量
const PI = 3.14;
PI = 3.15; // 不允许重新分配，会报错

Note:

• Variable names should follow camel case, i.e. word Connect with capital letters.
• Variable names cannot start with a number, but can start with an underscore (_).
• Variable names cannot be keywords or reserved words.

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