[RajatX24]

Fixes #173

Problem

rounds is bcrypt's cost factor (how many hashing iterations run). Valid values are integers from 4 to 31 (out-of-range integers are clamped to that range). genSaltSync never checked this, so a non-integer like 10.5 produced a broken salt, and the error only appeared later in hashSync.

import bcrypt from "bcryptjs";

const salt = bcrypt.genSaltSync(10.5); // "$2b$10.5$..." (invalid)
bcrypt.hashSync("my-password", salt);  // Error: Missing salt rounds

Fix

• genSaltSync now throws Illegal arguments: rounds must be an integer for non-integers (10.5, Infinity). genSalt inherits this (rejects or passes the error to the callback).
• hash(password, <number>) now forwards genSalt errors to the callback or promise. Before, they were dropped and users saw a misleading Invalid string / salt: Not a string.
• JSDoc and types.d.ts updated with @throws / @rejects.

After the fix:

bcrypt.genSaltSync(10.5); // Error: Illegal arguments: rounds must be an integer

Behavior change: genSaltSync(Infinity) used to be clamped to 31. It now throws, since Infinity is not an integer.

Tests

Added to tests/index.js, covering genSaltSync, genSalt (promise and callback), hashSync and hash:

• 10.5 and Infinity are rejected with the new error.
• Valid costs (4, 10, 31) still embed the right cost in the salt.

npm test, npm run lint and npm run build pass locally.

Will add a Loom video covering the changes

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Made with Operate, reviewed and tested locally.
Investigation: https://operatex.dev/open-source/github/dcodeIO/bcrypt.js/issues/173