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maxBy

TS JS Deno

Returns the maximum value of an array, after mapping each element to a value using the provided function.

Use Array.prototype.map() to map each element to the value returned by fn, Math.max() to get the maximum value.

typescript
export const maxBy = <T = any>(arr: T[], fn: MapFunc<T> | string) =>
  Math.max(...arr.map(isString(fn) ? (val: any) => val[fn] : fn));
typescript
maxBy([{ n: 4 }, { n: 2 }, { n: 8 }, { n: 6 }], (o) => o.n); // 8
maxBy([{ n: 4 }, { n: 2 }, { n: 8 }, { n: 6 }], "n"); // 8

const array = [
  new Date(2017, 4, 13),
  new Date(2018, 2, 12),
  new Date(2016, 0, 10),
  new Date(2016, 0, 9),
];
const timestamp = maxBy(array, (date) => date.getTime());
assertEquals(new Date(timestamp).toDateString(), "Mon Mar 12 2018");