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JS
JavaScript error

TypeError

The JavaScript exception "invalid assignment to const" occurs when it was attempted to alter a constant value. JavaScript const declarations can't be re-assigned or redeclared.

Reference entryJavaScriptFetched
This is a reference entry from MDN Web Docs. A full explanation with fixes has not been written yet.

The error messages

TypeError: Assignment to constant variable. (V8-based)
As listed by MDN Web Docs
TypeError: invalid assignment to const 'x' (Firefox)
As listed by MDN Web Docs
TypeError: Attempted to assign to readonly property. (Safari)
As listed by MDN Web Docs

Details

Category
TypeError
Severity
error
Runtime
both

Related errors

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Source: MDN Web Docs. Data fetched 2026-09-25T01:48:37.274Z.