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isNotIn()

isNotIn<T>(array): (...args) => boolean

Creates a predicate function that determines if a value does not exist in a given array.

Type Parameters​

T​

T

The type of the array elements and value

Parameters​

array​

T[]

The array to search within

Returns​

(...args): boolean

Parameters​

args​

...[T]

Returns​

boolean

Remarks​

  • Pure function with no side effects
  • Negation of isIn using functional composition
  • Uses strict equality (===) for element comparison
  • Works with any type that can be compared with strict equality

Example​

const isInvalidStatus = isNotIn(['pending', 'approved', 'rejected']);
isInvalidStatus('unknown');  // true
isInvalidStatus('pending');  // false

const isNotPrime = isNotIn([2, 3, 5, 7, 11, 13]);
isNotPrime(10); // true
isNotPrime(7);  // false

// Useful with arrays
const allowedIds = [101, 102, 103];
const allRequests = [101, 104, 102, 105];
const unauthorized = allRequests.filter(isNotIn(allowedIds)); // [104, 105]