➢The let keyword was introduced in ES6 (2015).
➢Variables defined with let cannot be Redeclared.
➢Variables defined with let must be Declared before use.
➢Variables defined with let have Block Scope.
Cannot be Redeclared
➢Variables defined with let cannot be redeclared.
➢You cannot accidentally redeclare a variable.
EXAMPLE:
let x = "BMR"; let x = 0;
// SyntaxError: 'x' has already been declared
Block Scope
➢Before ES6 (2015), JavaScript had only Global Scope and Function Scope.
➢ES6 introduced two important new JavaScript keywords: let and const.
➢These two keywords provide Block Scope in JavaScript.
➢Variables declared inside a { } block cannot be accessed from outside the block:
EXAMPLE:
{ let x = 0; } // x can NOT be used here
Redeclaring Variables
➢Redeclaring a variable using the let keyword can solve this problem.
➢Redeclaring a variable inside a block will not redeclare the variable outside the block:
EXAMPLE:
let x = 10; // Here x is 10
{ let x = 5; // Here x is 5
} // Here x is 10
