Generate a hash of a string

Compute the 32-bit hash Java’s String.hashCode uses.

JavaScript Version 1.0.0 · MIT · .md

function hashString(text) { return text.split('').reduce((hash, char) => (Math.imul(31, hash) + char.charCodeAt(0)) | 0, 0); }

Input & expected output

"hello"

99162322

The edge case

""

0

Know the limits

• Not cryptographic and collision-prone: use it for bucketing, never for integrity. To authenticate data use HMAC-SHA256, as in the webhook signature lab.

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

• Capitalize a string — Uppercase the first Unicode code point and preserve the remaining text.
• Reverse a string — Reverse Unicode code points without splitting surrogate pairs.
• Check a palindrome — Compare a string with its code-point reversal.