JavaScript
JavaScript assigned to an undeclared variable
ReferenceError: assignment to undeclared variable "x"
JavaScript threw because code assigned to a variable that was never declared in the current scope.
Error AtlasError Documentation and ResolutionObserved message
ReferenceError: assignment to undeclared variable "x"
Why it happens
- Code assigns to a variable name that was never declared.
- A typo created a new undeclared identifier instead of updating an existing one.
- Strict mode or module execution prevents implicit globals.
How to fix it
- Declare the variable explicitly before assignment.
- Check for spelling mistakes in variable names.
- Avoid relying on implicit globals and treat modules and strict mode as the default.
Official reference
MDN: ReferenceError: assignment to undeclared variable xRelated errors
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