如何在此 If 语句中创建 else if 和 else

Question

I have this if statement below. It is possible to add / make it in if - else if - else ?. If not tell me the reason. Thanks. Cheers

 var num1; var num2 = 1; num1 = num2 != 0 ? num2 : ""; alert(num1);

Answer 1

Sure but our (or at least my) human brain doesn't like reading it ;-)

num1 = num2 != 0  
            ? num2 
              : num3 != 0  
            ? num3 
              : num4 != 0  
            ? num4 
              : num5 != 0  
            ? num5 
              : ""

spacing is not required just makes it more readable.

Answer 2

If all you want is to translate the ternary operator (the ? : ) into an if else then here goes:

 var num1; var num2 = 1; if (num2 != 0) { num1 = num2; } else { num1 = ""; } alert(num1);

Answer 3

You're describing the ternary operator, and it's pretty much

if(part before ?) {
    (part before colon)
} else {
    (part after colon)
}

Like so:

if( num2 != 0 ) {
    num1 = num2;
} else {
    num1 = "";
}

In general, if you ever have anything more complicated than [a = (b==x) ? a : b], use an if block instead or risk pissing off your fellow programmers :-). Also use parens a lot to disambiguate, as order of operations can sometimes get weird...