Understanding JavaScript’s Math.max: Edge Cases and Array Tricks

Math.max is a built‑in JavaScript function that returns the largest value from a given set of numbers.

Syntax: Math.max(value1[, value2, ...]) Example with multiple arguments: Math.max(1, 2, 3); // => 3 When called with a single argument, the function simply returns that argument: Math.max(1); // => 1 If no arguments are provided, Math.max returns -Infinity, which represents the lowest possible numeric value.

Maximum of an array

You can find the maximum number in an array by using the spread operator:

const numbers1 = [1, 2, 3];
Math.max(...numbers1); // => 3

Maximum of two arrays

To compare the maximum values of two arrays, compute each maximum first and then compare them:

const numbers1 = [1, 2, 3];
const numbers2 = [0, 6];
const max1 = Math.max(...numbers1);
const max2 = Math.max(...numbers2);
Math.max(max1, max2); // => 6

If one of the arrays is empty, spreading it yields no arguments, so Math.max(...[]) behaves the same as Math.max() and returns -Infinity:

const numbers1 = [];
const numbers2 = [0, 6];
const max1 = Math.max(...numbers1); // -Infinity
const max2 = Math.max(...numbers2); // 6
Math.max(max1, max2); // => 6

Similarly, Math.min() with no arguments returns Infinity, making the statement Math.min() > Math.max() evaluate to true.

Visual summary: