insert unicode like \u1d6fc in a javascript text string

Question

I'm writing some code that scans a string for TeX-style Greek character (like \Delta or \alpha), and replaces the string with the Unicode symbol. It works fine for the non-italic Greek characters. The problem is that I want to use mathematical italic for the lower case. These codes are one digit longer. For example, the code for the letter alpha is 1d6fc. When I put \u1d6fc into my string it displays as the character that matches \u1d6f (a lower case m with a superimposed tilde) followed by the letter c. How do I force the "correct" reading of the code?

Answer 1

You have to use UTF-16 surrogate pairs for characters beyond the UTF-16 range. In your particular case, you can use 0xD835 0xDEFC:

    console.log('\uD835\uDEFC')

Here is a handy pair calculator. If you don't have to worry about Internet Explorer, you can also use String.fromCodePoint(), which will deal with that mess for you. If you do have to worry about Internet Explorer, MDN has a polyfill for that method.

Answer 2

To produce a \u escape sequence with more than 4 hex digits (code point belonging to a so-called astral plane), you can use the Unicode code point escape notation \u{xxxxx}:

console.log ('\u{1d6fc}');

or you can call String.fromCodePoint with the code point value expressed in hexadecimal using the 0x prefix notation:

console.log (String.fromCodePoint (0x1d6fc));