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What happens if you accidentally redeclare a variable with let in the same scope?

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What happens if you accidentally redeclare a variable with let in the same scope?

Asked on May 21, 2026

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If you accidentally redeclare a variable with "let" in the same scope, it will result in a SyntaxError. "let" does not allow redeclaration within the same block scope.

// Correct usage
        let x = 10;
        x = 20; // Reassigning is allowed

        // Incorrect usage
        let y = 30;
        let y = 40; // SyntaxError: Identifier 'y' has already been declared

Additional Comment:

"let" allows variable reassignment but not redeclaration in the same scope.
Attempting to redeclare a variable with "let" in the same block will throw a SyntaxError.
Use "let" for block-scoped variables when you need to reassign but not redeclare.

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What happens if you accidentally redeclare a variable with let in the same scope?

Asked on May 21, 2026

Answer

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