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JavaScript tried to reassign a const variable

TypeError: invalid assignment to const "x"

JavaScript threw because code attempted to assign a new value to a constant binding.

TypeError: invalid assignment to construntime

Observed message

TypeError: invalid assignment to const "x"

Why it happens

  • Code reassigns a variable declared with const.
  • A refactor changed a binding to const without updating later assignments.
  • Loop or conditional logic assumes the binding can change.

How to fix it

  1. Stop reassigning the const binding.
  2. Use let instead if the binding is meant to change.
  3. Distinguish between mutating an object value and reassigning the binding itself.

Official reference

MDN: TypeError: invalid assignment to const x

Related errors

ReferenceError: can't access lexical declaration before initializationJavaScript accessed a let or const binding before initializationReferenceError: assignment to undeclared variableJavaScript assigned to an undeclared variableTypeError: class constructors must be invoked with 'new'JavaScript class constructor was called without newRangeError: x can't be converted to BigInt because it isn't an integerJavaScript could not convert a non-integer value to BigInt

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JavaScript invalid assignment to const: causes and fixes | Error Atlas