once() function

Creates a function that invokes f only on its first call. Subsequent calls return the result of the first invocation without calling f again.

The returned function preserves this and the arguments of f.

Signature:

declare function once<F extends (...args: any[]) => any>(f: F): F;

Example

let count = 0;
const init = once((a: number) => {
  count += 1;
  return a * 10;
});

init(1); // 10 - `f` is called
init(2); // 10 - `f` is not called again, first result is returned
count; // 1

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