What this snippet does
Map preserves insertion order and handles any key type — ideal for frequency counting and histogram building.
Expected output
b: 1 a: 3 n: 2 [ [ 'a', 3 ], [ 'n', 2 ], [ 'b', 1 ] ]
Why practise typing this
Typing map 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
- Map basicsMap · beginner
- Map vs ObjectMap · intermediate
- let vs constVariables · beginner
- const configVariables · beginner
- const mutationVariables · beginner
- var hoistingVariables · beginner