What is the ?: syntax in JavaScript? [duplicate]

Question

what does it mean for the following line?

T = ($("#a .b").hasClass("active") ? "C" : "D") ;

$("#a .b").hasClass("active") means whether #a .b exists? but how about ? "C" : "D", is it some kind of comparison logic?

Answer 1

It's a ternary operator

condition ? expr1 : expr2 

If condition is true then expr1 would return else expr2 will return.

So, in your case:

T = ($("#a .b").hasClass("active") ? "C" : "D") ;

T variable will hold "C" if $("#a .b") has class active else it would hold "D"