implicit coercion in JavaScript

What this snippet does

JavaScript converts types automatically in arithmetic — + with a string causes string concatenation, while -, *, / convert to numbers.

Expected output

12
3
2
0
1
NaN

Why practise typing this

Typing types 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

• typeof operatorTypes · beginner
• typeof nullTypes · beginner
• loose equalityTypes · intermediate
• explicit conversionTypes · intermediate
• let vs constVariables · beginner
• const configVariables · beginner