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JS
JavaScript error

ReferenceError

The JavaScript exception "must call super constructor before using 'this' in derived class constructor" occurs when the super() is not called for a given derived class constructor, and the derived constructor tries to access the value of this, or the derived constructor has already returned and the return value is not an object.

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

The error messages

ReferenceError: Must call super constructor in derived class before accessing 'this' or returning from derived constructor (V8-based)
As listed by MDN Web Docs
ReferenceError: must call super constructor before using 'this' in derived class constructor (Firefox)
As listed by MDN Web Docs
ReferenceError: 'super()' must be called in derived constructor before accessing |this| or returning non-object. (Safari)
As listed by MDN Web Docs

Details

Category
ReferenceError
Severity
error
Runtime
both

Related errors

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