将if语句转换为三元运算符

Question

I tried to convert these if statement to ternary:

var eatsPlants = false;
var eatsAnimals = true;

    if(eatsPlants){
      return 'herbivore';
    }else if(eatsAnimals){
      return 'carnivore';
    }else if(eatsPlants && eatsAnimals){
    return 'omnivore';
    }else{
     return undefined;
    }

Here's my solution:

var category = eatsPlants && eatsAnimals ? "omnivore" : "herbivore" : "carnivore" : undefined;

console.log(category);

But this doesnt work and it returns the error missing semicolon.

Any idea how to fix it?

Answer 1

You forgot the other two conditions, and changed the order of checks (which is actually necessary to make it work, though). You'd do either

return (eatsPlants && eatsAnimals
  ? 'omnivore'
  : (eatsPlants
    ? 'herbivore'
    : (eatsAnimals
      ? 'carnivore'
      : undefined)));

or, avoiding the AND operation by nesting,

return (eatsPlants
  ? (eatsAnimals
    ? 'omnivore'
    : 'herbivore')
  : (eatsAnimals
    ? 'carnivore'
    : undefined));

(The parenthesis and indentation are optional, but strongly encouraged for readability, at least one of them).

Answer 2

You should add the remaining if conditions too

var category = eatsPlants && eatsAnimals ? "omnivore" : eatsPlants? "herbivore" : eatsAnimals? "carnivore" : undefined;

console.log(category);

Answer 3

The js snippet shared by you may throw an error as return statement is not inside a function.

Have created one more variable returnResult which will be assinged with new value depending on the condition.

!1 is false & !0 is true, void 0 is undefined

var eatsPlants = !1, eatsAnimals = !0, returnResult = "";
returnResult = eatsPlants ? "herbivore" : eatsAnimals ? "carnivore" : eatsPlants && eatsAnimals ? "omnivore" : void 0;