spread operator in JavaScript

What this snippet does

Spreading arrays creates a shallow copy — mutations to the copy don't affect the original for flat arrays.

Expected output

[ 1, 2, 3, 4, 5, 6 ]
[ 1, 2, 3 ]
[ 1, 2, 3, 99 ]

Why practise typing this

Typing spread code builds muscle memory for the symbols and indentation JavaScript uses most, which prose-based typing tests never cover. DevType measures your words per minute and accuracy on this snippet and tracks the individual characters you mistype, so later lessons can target them.

More JavaScript practice

• spread argsSpread · beginner
• string spreadSpread · beginner
• let vs constVariables · beginner
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• const mutationVariables · beginner
• var hoistingVariables · beginner