Check if a value is a string

Use Object.prototype.toString so String objects count too.

JavaScript Version 1.0.0 · MIT · .md

function isString(value) { return Object.prototype.toString.call(value) === '[object String]'; }

Input & expected output

"ana"

true

The edge case

8812

false

Know the limits

• typeof value === "string" is enough unless you must accept new String() objects.

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.