Check if a string contains only digits

Test for one or more ASCII digits.

JavaScript Version 1.0.0 · MIT · .md

function isNumeric(text) { return /^[0-9]+$/.test(text); }

Input & expected output

"8812"

true

The edge case

""

false

Know the limits

• The original returned true for the empty string; this version requires at least one digit.
• Signs, decimal points and spaces fail.

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

• Check whether all values are equal — Compare every item with the first using Object.is.
• Check whether an object is empty — Check for own enumerable string keys on a JSON object.
• Check whether an integer is even — Test parity for safe integers, including zero and negative values.