Spread in function calls

Learn to spread an array's elements as function arguments.

Spread in calls

Spread also works in a function call. Writing Math.max(...scores) passes every element of the scores array as a separate argument; it is the same as Math.max(85, 92, 78).

This is handy with Math.max, Math.min or any multi-parameter function you write. Instead of passing the array as one argument, you expand its elements.

The old way: apply

Before spread, passing an array as arguments meant using apply: Math.max.apply(null, scores). It works, but it is hard to read; passing null is a trick to ignore the this binding.

Modern code prefers Math.max(...scores). It gives the same result, is shorter, and shows the intent clearly. When you see apply in old code, know it can now be replaced with spread.

Exercise Compute the invoice with spread

Write a function called calculateTotal(price, tax, discount). In its body, return price + tax - discount. Create an array called invoice (for example [100, 18, 10]). Use spread to pass the elements of invoice as arguments to calculateTotal and log the result with console.log.

Show example solution

function calculateTotal(price, tax, discount) {
  return price + tax - discount;
}
const invoice = [100, 18, 10];
console.log(calculateTotal(...invoice));

Test yourself

What does `Math.max(...nums)` do?
```
const nums = [85, 92, 78];
const top = Math.max(...nums);
```
- It passes the `nums` array itself as a single argument
- It passes each element of `nums` as a separate argument
- It passes the value of `nums.length`
- It sorts the `nums` array alphabetically
Show answer

It passes each element of `nums` as a separate argument — Correct. Spread expands the array; each element becomes its own argument.
Match the call styles

Math.max(...nums)

Find the largest value
fn.apply(null, arr)

Old way
...arr (in a call)

Expand array into arguments

Find the highest score

const scores = [85, 92, 78];
const highest = Math.max(____);
console.log(highest);

Show answer

const scores = [85, 92, 78];
const highest = Math.max(...scores);
console.log(highest);

Next lesson: Summary - Spread and rest

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