Pick keys from object in TypeScript

Selects keys from an object and gets a correctly narrowed type back.

function pick<T extends object, K extends keyof T>(
  obj: T,
  keys: K[],
): Pick<T, K> {
  const out = {} as Pick<T, K>;
  for (const key of keys) {
    if (key in obj) {
      out[key] = obj[key];
    }
  }
  return out;
}

Keywords and builtins used here

• K
• T
• as
• const
• extends
• for
• function
• if
• of
• return

The run, in numbers

Lines

12

Characters to type

199

Tokens

76

Three-star pace

105 tpm

At the three-star pace of 105 tokens a minute, this run takes about 43 seconds.

Type this snippet

Step 1 of 11 in Generic helpers, step 9 of 20 in Generics.

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