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let Statement

Easy

In plain terms

let declares a block-scoped variable. Unlike var, it is only visible inside the block (curly braces) where it is declared. This prevents accidental reassignment and scope leaks.

What you need to know

  • •Block-scoped
  • •Temporal Dead Zone until declaration
  • •Recommended for mutable variables

Try it yourself

Copy the code below and run it in your browser console or a code editor:

{
  let x = 10;
  console.log(x); // 10
}
// console.log(x); // Error: x is not defined

for (let i = 0; i < 3; i++) {
  console.log(i); // 0, 1, 2 - each iteration has its own i
}

Learn more

Dive deeper with these trusted resources:

MDNjavascript.infoTutorialsPointW3Schools