Answer by ehmicky for String length in bytes in JavaScript

Based on the following benchmarks, this appears to be the fastest choice that works on all platforms:

• In Node.js: Buffer.byteLength(string).
• Otherwise:
  • new TextEncoder().encode(string).length on big strings.
  • String.charCodeAt() (as described here) on small strings. At what point a string is "big" depends on your machine (for me, it's roughly 300 characters).

I have created the following library that implements the above:

import stringByteLength from 'string-byte-length'stringByteLength('test') // 4stringByteLength('') // 1stringByteLength('\0') // 1stringByteLength('±') // 2stringByteLength('★') // 3stringByteLength('🦄') // 4