Typed memoize in TypeScript

Memoization that keeps the original signature intact.

function memoize<A extends unknown[], R>(
  fn: (...args: A) => R,
): (...args: A) => R {
  const cache = new Map<string, R>();
  return (...args: A): R => {
    const key = JSON.stringify(args);
    if (!cache.has(key)) {
      cache.set(key, fn(...args));
    }
    return cache.get(key) as R;
  };
}

Keywords and builtins used here

• A
• JSON
• Map
• as
• const
• extends
• function
• if
• return
• string

The run, in numbers

Lines

12

Characters to type

272

Tokens

103

Three-star pace

105 tpm

At the three-star pace of 105 tokens a minute, this run takes about 59 seconds.

Type this snippet

Step 1 of 5 in Timing & memory, step 14 of 19 in Classes & patterns.

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