How to use five digit long Unicode characters in J

Question

In JavaScript I can do this:

foo = "\u2669" // 1/4 note

But I can't do this

foo = "\u1D15D" // full note  -five hex digits

It will be interpreted as "\u1D15" followed by "D"

Are there any workarounds for this?

UPDATE 2012-07-09: The proposal for ECMAScript Harmony now includes support for all Unicode characters.

Answer 1

I did a little checking and it appears that there is no full note near 0x2669. (table of unicode chars)

Although using 0x01D15D does give me a unknown unicode character this could be because I don't have a music font though. Javascript will try to parse as byte as it can and 0x1D15D is 2.5 bytes padding it with a 0 will make it 3 and parsable.

Also this was quite handy: unicode.org/charts/PDF/U1D100.pdf

Answer 2

Try putting the unicode between curly braces: '\u{1D15D}'.

Answer 3

In the MDN documentation for fromCharCode, they note that javascript will only naturally handle characters up to 0xFFFF. However, they also have an implementation of a fixed method for fromCharCode that may do what you want (reproduced below):

function fixedFromCharCode (codePt) {
    if (codePt > 0xFFFF) {
        codePt -= 0x10000;
        return String.fromCharCode(0xD800 + (codePt >> 10), 0xDC00 + (codePt & 0x3FF));
    }
    else {
        return String.fromCharCode(codePt);
    }
}

foo = fixedFromCharCode(0x1D15D);

Answer 4

You can use this:

function fromOutsideBMP(cp) {
// 0x01D120
  var x=cp-0x10000;
  var top10=parseInt("11111111110000000000",2);
  var end10=parseInt("1111111111",2);
  var part1=(x&top10)/1024+0xD800;
  var part2=(x&end10)+0xDC00;
  var s=String.fromCharCode(part1)+String.fromCharCode(part2);
  return s;
}

Example:

> fromOutsideBMP(0x01d122)
  "                                                                    

                                                        
            

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