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negate

negate() function​

Create a function that returns the opposite result of a predicate function

Signature: 
declare function negate<T>(predicate: (input: T) => boolean): (input: T) => boolean;

declare function negate<T, N extends T>(predicate: (input: T) => input is N): (input: T) => input is Exclude<T, N>;

Example​

const isDefined: (input: string | undefined) => input is string = negate(isUndefined)<string | undefined>

const isDefined: (input: unknown) => boolean = negate((input) => input === undefined)

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