Decoding cp1251 to UTF-8 in javascript

Question

How to decode cp-1251 to UTF-8 in javascript?

The cp-1251 is from a datafeed, which required to decode from js client side.

There is no way to change server side output, since it is related to a 3rd party, and due to some reason, I would not use any server side programming to convert the datafeed to become another datafeed.

Answer 1

(Assuming that by "UTF-8" you meant the JS strings in their native encoding...)

Depending on the format your 'cp-1251' data is in and depending on the browsers you need to support, you can choose from:

• TextDecoder.decode() API (decodes a sequence of octets from a typed array, like Uint8Array) - if you're using web sockets, you can get an ArrayBuffer out of it to decode.
• https://github.com/mathiasbynens/windows-1251 operates on something it calls 'byte strings' (JS Strings consisting of characters like \u00XY, where 0xXY is the encoded byte.
• build the decoding table yourself (example)

Note that in most cases (not something as low-level as websockets though) it might be easier to read the data in the correct encoding before it ends up as a JS string (for example, you can force XMLHttpRequest to use a certain encoding even if the server misreports the encoding).