Convert a string to a number

Use unary plus.

JavaScript Version 1.0.0 · MIT · .md

function toNumber(text) { return +text; }

Input & expected output

"42.5"

42.5

The edge case

""

0

Know the limits

• The empty string becomes 0 and invalid text becomes NaN (null in JSON). Validate first, or use Number.parseFloat for partial parsing.

The function above is the implementation used by the lab. The lab validates JSON types and caps size before execution; include equivalent validation when accepting untrusted input in your application.

Keep exploring

• Clamp a number to a range — Keep a number inside an inclusive minimum and maximum.
• Round to a number of digits — Apply decimal scaling and JavaScript rounding for display-oriented values.
• Add an ordinal suffix to a number — Append st, nd, rd or th to a positive integer.