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Lesson 9 — Spread & rest
The ... operator
Spread (...arr) expands an array into its separate items, for example inside a new array literal. You can spread several arrays and mix in single values. Rest looks the same but works the other way: ...args in a parameter list collects leftover arguments into an array.
const nums = [2, 3];
const more = [1, ...nums, 4]; // [1, 2, 3, 4]
Why it matters: spreading is the standard way to copy and combine arrays without changing the originals.
Want it another way?
Task
Merge both arrays into all with spread, so it logs [1, 2, 3, 4].
Run your code — when the output matches the task, you will see a green check. Then mark the lesson complete.
Test your knowledge
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