What is the difference between var, let and const?

Point	var	let	const
Scope	Function	Block	Block
Reassign	Yes	Yes	No
Redeclare	Yes	No	No
Hoisting	Hoisted, value undefined	Hoisted, but unusable before declaration	Same as let

if (true) {
  var a = 1;
  let b = 2;
}
console.log(a);
console.log(b);

Output:

Use const by default, let if the value must change, and avoid var. See JavaScript Variables and Scope.

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