Could it be possible to add the integer type to the ECMAScript standard?

Question

In JavaScript, every number you will ever use will always be represented with what C programmer would call a double. The official type is I believe number. If I recall correctly, that fact was mentioned by Google as a "fundamental" problem with JavaScript and one of the reason why they wanted to have clean break with Dart. Now, I can't help but wonder :

• Can the ECMAScript standard just add that type? Would it be possible to do without breaking existing code?
• Anyway, can't a JIT engine watch the integer usage and generate code that is almost as efficient as using a native integer type, by using integer registers and opcodes?

In effect : Could it be done? Why should it be done?

• Robert Harvey: Javascript 2.0 has that, and more. www-archive.mozilla.org/js/language/js20-1999年02月18日/types.html. Hopefully we can get support in modern browsers in the next few years.
• Hubert OG: Question: what does 9999999999999999 % 9 evaluate to? ;)
• user949300: @Robert Harvey: maybe support in the next couple of decades, considering that spec is nearly old enough to drink. :-)

Answer 1

As for your second point, yes, integer use can be detected. Firefox does it as part of their asm.js feature. It's not entirely straightforward: for example, adding two integers may overflow. That wont happen if the values were added as double. To account for this, every expression that should produce a true 32 bit int is appended with | 0, which does nothing except forcing the result to be an int.

• Laurent Bourgault-Roy: I see. Could it be done non asm.js code though?
• user949300: Much like there are JS classes for complex numbers, you could write an int class that has add(), subtract() etc. and it does the | 0 trick. I suspect somebody has already done this??? Or are you more concerned about performance?