JavaScriptEasy
What are the differences between JavaScript variables created using let, var or const?
By FrontendPro Editorial Team Updated 8/8/2026
#JavaScript
Answer
In JavaScript, let, var, and const are all keywords used to declare variables, but they differ significantly in terms of scope, initialization rules, whether they can be redeclared or reassigned, and the behavior when they are accessed before declaration:
| Behavior | var | let | const |
|---|---|---|---|
| Scope | Function or Global | Block | Block |
| Initialization | Optional | Optional | Required |
| Redeclaration | Yes | No | No |
| Reassignment | Yes | Yes | No |
| Accessing before declaration | undefined | ReferenceError | ReferenceError |
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