Question:
I encountered syntax in a JavaScript program that I recognized from C/C++ syntax as well. The code was something to the effect of xxxxxx?yyyyyyy:zzzzz. I am fairly sure that it is an alternative syntax for an if-then statement, but I’m not sure exactly how it works. Can you give me a translation from this syntax to a conventional if-then statement?

Answer:

Yes. You’ve found an often overlooked operator built into the JavaScript language. Called the tertiary operation, because it requires three parts, this operator is a handy shortcut for an if-then block, but sometimes it’s even better because it returns an expression. The first part of the operator is an expression that evaluates to either true or false. If this is true, then the expression is set to the value of the second part of the operator otherwise the third part is used. For example, in this code, if the variable x equals 5 then variable y is set to x times two, otherwise 15.

y = (x == 5) ? x * 2 : 15;

This would be similar to:

if (x == 5) {    y = x * 2;} else {    y = 15;}