How can I convert a string into a unicode character?

String.fromCharCode("0x" + input)

or

String.fromCharCode(parseInt(input, 16)) as they are 16bit numbers (UTF-16)

Use String.fromCharCode() like this: String.fromCharCode(parseInt(input,16)). When you put a Unicode value in a string using \u, it is interpreted as a hexdecimal value, so you need to specify the base (16) when using parseInt.