Insert Unicode character into JavaScript

Insert Unicode character into JavaScript

I need to insert an Omega (Ω) onto my html page. I am using its HTML escaped code to do that, so I can write Ω and get Ω. That’s all fine and well when I put it into a HTML element; however, when I try to put it into my JS, e.g. var Omega = Ω, it parses that code as JS and the whole thing doesn’t work. Anyone know how to go about this?

Solutions/Answers:

Solution 1:

I’m guessing that you actually want Omega to be a string containing an uppercase omega? In that case, you can write:

var Omega = '\u03A9';

(Because Ω is the Unicode character with codepoint U+03A9; that is, 03A9 is 937, except written as four hexadecimal digits.)

Solution 2:

Although @ruakh gave a good answer, I will add some alternatives for completeness:

You could in fact use even var Omega = 'Ω' in JavaScript, but only if your JavaScript code is:

  • inside an event attribute, as in onclick="var Omega = '&#937';
    alert(Omega)"
    or
  • in a script element inside an XHTML (or XHTML + XML) document
    served with an XML content type.

In these cases, the code will be first (before getting passed to the JavaScript interpreter) be parsed by an HTML parser so that character references like Ω are recognized. The restrictions make this an impractical approach in most cases.

You can also enter the Ω character as such, as in var Omega = 'Ω', but then the character encoding must allow that, the encoding must be properly declared, and you need software that let you enter such characters. This is a clean solution and quite feasible if you use UTF-8 encoding for everything and are prepared to deal with the issues created by it. Source code will be readable, and reading it, you immediately see the character itself, instead of code notations. On the other hand, it may cause surprises if other people start working with your code.

Using the \u notation, as in var Omega = '\u03A9', works independently of character encoding, and it is in practice almost universal. It can however be as such used only up to U+FFFF, i.e. up to \uffff, but most characters that most people ever heard of fall into that area. (If you need “higher” characters, you need to use either surrogate pairs or one of the two approaches above.)

You can also construct a character using the String.fromCharCode() method, passing as a parameter the Unicode number, in decimal as in var Omega = String.fromCharCode(937) or in hexadecimal as in var Omega = String.fromCharCode(0x3A9). This works up to U+FFFF. This approach can be used even when you have the Unicode number in a variable.

Solution 3:

The answer is correct, but you don’t need to declare a variable.
A string can contain your character:

"This string contains omega, that looks like this: \u03A9"

Unfortunately still those codes in ASCII are needed for displaying UTF-8, but I am still waiting (since too many years…) the day when UTF-8 will be same as ASCII was, and ASCII will be just a remembrance of the past.