Map over an optional in TypeScript

Applies a function only when the value is not null or undefined.

function maybeMap<T, U>(
  value: T | undefined,
  fn: (value: T) => U,
): U | undefined {
  return value === undefined ? undefined : fn(value);
}

Keywords and builtins used here

• T
• fn
• function
• return

The run, in numbers

Lines

6

Characters to type

140

Tokens

43

Three-star pace

105 tpm

At the three-star pace of 105 tokens a minute, this run takes about 25 seconds.

Type this snippet

Step 11 of 11 in Generic helpers, step 19 of 20 in Generics.

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