尝试弄清楚如何将具有多个条件的长三元运算符转换为长 if 语句

Question

I found online this snippet and I'm trying to figure it out how to translate it in a plan if statement:

return a.price > b.price ? 1 : a.price === b.price ? a.name > b.name ? 1 : -1 : -1;

In my opinion, if I had written an if statement:

if (a.price > b.price) {
    return 1;
} else if (a.price === b.price) {
    return 1;
} else if (a.name > b.name) {
    return 1;
} else {
    return -1;
}

But I'm not quite sure what it means a question mark and right after another question mark, same problem with a colon. I get that, the colon, in this case, could be an else if statement (in that order), but what about the question mark? any hint?

Answer 1

Your first part is right, but the next isn't. This:

a.price === b.price ? a.name > b.name ? 1 : -1 : -1;

separated out, looks like:

a.price === b.price
  ? (
    a.name > b.name
      ? 1
      : -1
    )
  : -1;

The inner conditional is a.name > b.name ? 1 : -1 a.name > b.name ? 1 : -1 .

If the prices are not equal, -1 is returned. Otherwise, the names are compared. To translate this correctly:

if (a.price > b.price) {
  return 1;
}
if (a.price !== b.price) {
  return -1;
}
if (a.name > b.name) {
  return 1;
}
return -1;

If this is being used for a .sort callback, another option which is equivalent to the above is:

return a.price - b.price || a.name.localeCompare(b.name)

Answer 2

Grouping it like this will help

a.price > b.price ? 1 : (a.price === b.price ? (a.name > b.name ? 1 : -1) : -1)

a.price > b.price ? 1 : x
x = a.price === b.price ? y : -1;
y =  a.name > b.name ? 1 : -1; 

The translated IF ELSE would be

if(a.price > b.price){
    return 1
} else {
    if(a.price === b.price){
        if(a.name > b.name){
            return 1;
        } else {
            return -1;
        }
    } else {
        return -1;
    }
}