How many bytes in a JavaScript string?

Question

I have a javascript string which is about 500K when being sent from the server in UTF-8. How can I tell its size in JavaScript?

I know that JavaScript uses UCS-2, so does that mean 2 bytes per character. However, does it depend on the JavaScript implementation? Or on the page encoding or maybe content-type?

Answer 1

This function will return the byte size of any UTF-8 string you pass to it.

function byteCount(s) {     return encodeURI(s).split(/%..|./).length - 1; } 

Source

JavaScript engines are free to use UCS-2 or UTF-16 internally. Most engines that I know of use UTF-16, but whatever choice they made, it’s just an implementation detail that won’t affect the language’s characteristics.

The ECMAScript/JavaScript language itself, however, exposes characters according to UCS-2, not UTF-16.

Source