Elliot Bonneville Elliot Bonneville - 3 months ago 23
Javascript Question

A somewhat painful triple-nested ternary operator

I went looking through

Raphael.js
's source code to find out how he converted RGB values to HSB. I found out the function he did it in and I was in the process of converting it to Python when I bumped into this nice triple-nested ternary operator:

H = (C == 0 ? null :
V == r ? (g - b) / C :
V == g ? (b - r) / C + 2 :
(r - g) / C + 4
);


It threw me for a loop because Python doesn't have the same kind of ternary operator that Javascript does. I spent a while looking over it and eventually hashed this somewhat saner code (using only if/else) out of it:

if (C == 0) {
H = null;
} else {
if(V == r) {
H = (g - b) / C;
} else {
if(V == g) {
H = (b - r) / C + 2;
} else {
H = (r - g) / C + 4;
}
}
}


Was my interpretation correct? I'm only asking this because if it isn't correct, I'm faced with a lot of debugging. So. Did I "get it"?

Answer

I think you can have this to avoid the deep nesting:

var H

if(C == 0){
    H = null;
}
else if(V == r){
    H = (g - b) / C;
}
else if (V == g){
    H = (b - r) / C + 2;
}
else {
    H = (r - g) / C + 4;
}
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