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Rest Parameters

Easy

In plain terms

Rest parameters ...args collect all remaining arguments into an array. Must be the last parameter. Replaces the need for the arguments object. Works with arrow functions.

What you need to know

  • •...args collects rest
  • •Must be last param
  • •Real array (unlike arguments)

Try it yourself

Copy the code below and run it in your browser console or a code editor:

function sum(...numbers) {
  return numbers.reduce((a, b) => a + b, 0);
}
sum(1, 2, 3, 4);  // 10

function log(first, ...rest) {
  console.log('First:', first);
  console.log('Rest:', rest);
}
log('a', 'b', 'c');  // First: a, Rest: ['b', 'c']

const multiply = (mul, ...nums) =>
  nums.map(n => n * mul);
multiply(2, 1, 2, 3);  // [2, 4, 6]

Learn more

Dive deeper with these trusted resources:

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