Omitting the second expression when using the if-else shorthand
Another option:
x === 2 ? doSomething() : void 0;
What you have is a fairly unusual use of the ternary operator. Usually it is used as an expression, not a statement, inside of some other operation, e.g.:
var y = (x == 2 ? "yes" : "no");
So, for readability (because what you are doing is unusual), and because it avoids the "else" that you don't want, I would suggest:
if (x==2) doSomething();
This is also an option:
x==2 && dosomething();
dosomething()
will only be called if x==2
is evaluated to true. This is called Short-circuiting.
It is not commonly used in cases like this and you really shouldn't write code like this. I encourage this simpler approach:
if(x==2) dosomething();
You should write readable code at all times; if you are worried about file size, just create a minified version of it with help of one of the many JS compressors. (e.g Google's Closure Compiler)
If you're not doing the else, why not do:
if (x==2) doSomething();