Why does this work:
And this doesn’t:
document.getElementById("emoji").innerHTML = String.fromCharCode(parseInt('1f604', 16));
A ‘char’ in JS terms is actually a UTF-16 code unit, not a full Unicode character. (This sad state of affairs stems from ancient times when there wasn’t a difference*.) To use a character outside of the Basic Multilingual Plane you have to write it in the UTF-16-encoded form of a surrogate pair of two 16-bit code units:
In ECMAScript 6 we will get some interfaces that let us deal with strings as if they were full Unicode code points, though they are incomplete and are only a façade over the String type which is still stored as a code unit sequence. Then we’ll be able to do:
See this question for some polyfill code to let you use this feature in today’s browsers.
(*: When I get access to a time machine I’m leaving Hitler alone and going back to invent UTF-8 earlier. UTF-16 must never have been!)
You can also use the hacky method if you don’t want to include
String.fromCodePoint() in your code. It consists in creating a virtual element …
… Filling it with the Working HTML…
elem.innerHTML = "😄"
… And finally getting its value
value = elem.innerHTML
To make it short, this works because of the fact that, as soon as you set the value of a HTML container, the value gets converted into the corresponding character.
Hope I could help.