Paul Biggar Paul Biggar - 8 months ago 45
Javascript Question

How many bytes in a JavaScript string?

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?


String values are not implementation dependent, according the ECMA-262 3rd Edition Specification, each character represents a single 16-bit unit of UTF-16 text:

4.3.16 String Value

A string value is a member of the type String and is a finite ordered sequence of zero or more 16-bit unsigned integer values.

NOTE Although each value usually represents a single 16-bit unit of UTF-16 text, the language does not place any restrictions or requirements on the values except that they be 16-bit unsigned integers.