JavaScript SyntaxError – Invalid destructuring assignment target

A JavaScript “SyntaxError: Invalid destructuring assignment target” error arises when the interpreter finds an invalid target on the left side of destructuring assignment, destructuring assignment makes it possible to unpack values from arrays or properties from objects into distinct variables but this can only be done with a correct syntax and target for such assignments.

Understanding an error

In JavaScript, an "Invalid destructuring assignment target" error means that either the syntax for the destructuring assignment is wrong or the pattern (array/object destructuring) does not match to assign targets when JavaScript has data being destructured it expects valid patterns that are similar to their structure, let’s look at this error, what causes it and how it can be resolved by giving examples.

Case 1: Error Cause: Incorrect Array Destructuring

Example: Making use of wrong syntaxes or invalid patterns in array destructuring assignment bring about such an error.

let [x, y, z] = 5;
console.log(x, y, z);

Output:

SyntaxError: Invalid destructuring assignment target

Resolution of error

On the right hand side of array destructuring assignment there should be an iterable source such as an array or any other iterable objects.

let [x, y, z] = [1, 2, 3];
console.log(x, y, z);

1 2 3

Case 2: Error Cause: Incorrect Object Destructuring

Example: If you use incorrect patterns or try to destructure non-object values in an object destructuring assignment this error will be thrown.

let { name, age } = 5;
console.log(name, age);

Output:

SyntaxError: Invalid destructuring assignment target

Resolution of error

Object destructuring assignment requires an object on the right-hand side with properties matching the destructuring pattern.

let { name, age } = { name: 'Pankaj', age: 20 };
console.log(name, age); 

Pankaj 20

Case 3: Error Cause: Invalid Pattern Matching

Example: You will get this error when you try destructuring an object without stating property names that exist or using mismatch patterns to do so.

let { a, b } = { c: 'foo', d: 'bar' };
console.log(a, b);

Output:

SyntaxError: Invalid destructuring assignment target

Resolution of error

Make it a point to have the names for properties there in a destructuring pattern correspond with those in an object where it is pulled apart.

let { c, d } = { c: 'foo', d: 'bar' };
console.log(c, d);

foo bar

Conclusion

To avoid “Invalid destructuring assignment target” errors in JavaScript, ensure that the structure of arrays or objects being destructured matches with both the assignment targets and de-structuring patterns, proper unpacking of values into distinct variables depends on conforming to JavaScript’s rules of syntax for destructing assignments leading to those “Invalid destructuring assignment target”.

pankajbind

Follow

Improve

Article Tags :

• JavaScript
• Web Technologies
• JavaScript-Errors