JavaScript let statement

　JavaScript Statements and Variable Declarations

letThe statement declares a block {} local variable scope and can optionally initialize it with a value.

let allows you to declare variables whose scope is limited to the block, statement, or expression where the variable is used.

This isvarThe keyword is different, this keyword defines a variable in the global scope or in the local function scope regardless of the block scope.

You can find more information in ourIn the JavaScript scope tutorialLearn more about variable scope.

Syntax:

let identifier = value;

let y = "world";

Browser compatibility

The numbers in the table specify the first browser version that fully supports the let statement:

Parameter value

Technical Details

More examples

When used within the block,letLimit the scope of the variable to within this block:

var a =　1;
var b =　2;
if (a ==　1) {
　　　var a =　11;　　//　a is in global scope
　　　let b =　22;　　//　The scope of b is within the if code block
　　　document.writeln(a);　　//　11
　　　document.writeln(b);　　//　22
}　
document.writeln(a);　　//　11
document.writeln(b);　　//　2

Also see

JavaScript Tutorial:JavaScript Variables

JavaScript Tutorial:JavaScript Scope

　JavaScript Statements and Variable Declarations