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Destructuring Undefined: What It Means and How to Fix It

Error reference

Destructuring Undefined

Language

JavaScript

Severity

High

When it happens

This TypeError occurs when you try to destructure properties from a value that is null or undefined.

Potential fixes

Provide a fallback with nullish coalescing: const { x } = getValue() ?? {}. Add a default value in the function signature: function fn({ x = 0 } = {}). Always initialize state to an empty object rather than undefined when awaiting async data.

Related errors

Cannot read properties of undefinedTypeErrornull is not an object

Deep dive

This TypeError occurs when you try to destructure properties from a value that is null or undefined. Destructuring requires the right-hand side to be an object or array; null and undefined cannot be destructured.

Why it happens

  • •A function or API call returns undefined when an object was expected.
  • •An async data fetch has not resolved yet and the state is still undefined.
  • •A conditional return path leaves the value undefined in some cases.
  • •Destructuring from an optional function parameter that was not provided.

Potential fixes

Provide a fallback with nullish coalescing: const { x } = getValue() ?? {}. Add a default value in the function signature: function fn({ x = 0 } = {}). Always initialize state to an empty object rather than undefined when awaiting async data.

Examples

JavaScript

Code that triggers the error

function getUser() {
  return undefined;
}
const { name, email } = getUser();

Error output

TypeError: Cannot destructure property 'name' of undefined as it is undefined.

Fixed code

function getUser() {
  return undefined;
}
const { name, email } = getUser() ?? {};
console.log(name); // undefined (no throw)

Practice in English

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"I hit an error...

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