Javascript reads only first elements(from array) in nested for loops

Question

I have the following issue. There's a problem I have to solve.

Fruit or Vegetable Write a JS function to print "fruit" , "vegetable" or "unknown" depending on the input string.

• Fruits are: banana, apple, kiwi, cherry, lemon, grapes, peach

• Vegetable are: tomato, cucumber, pepper, onion, garlic, parsley

• All others are unknown

  The input comes as array of one string element, the name of the fruit. The output should be printed to the console.

Example: input ['banana'] output: fruit
Example: input ['cucumber'] output: vegetable
Example: input ['pizza'] output: unknown

and I've tried something like that.

function fruitOrVegetable(inputArr) {
  var fruits = ['banana', 'apple', 'kiwi', 'cherry', 'lemon', 'grapes', 'peach'];
  var vegetables = ['tomato', 'cucumber', 'pepper', 'onion', 'garlic', 'parsley'];

  for (var i = 0; i < inputArr.length; i++) {
    for (var j = 0; j < fruits.length; j++) {
      for (var k = 0; k < vegetables.length; k++) {
        if (inputArr[i] === fruits[j]) {
          return ' fruit ';
        } else if (inputArr[i] === vegetables[k]) {
          return 'vegetable';
        } else {
          return 'unknown';
        }
      }
    }
  }
}

console.log(fruitOrVegetable(['tomato'])); //Returns vegetable
console.log(fruitOrVegetable(['banana'])); //Returns fruit
console.log(fruitOrVegetable(['cucumber'])); //Returns unknown
console.log(fruitOrVegetable(['pizza'])); // Returns unknown
console.log(fruitOrVegetable(['appple'])); //Returns unknown

Don't know why , but it works only for the 0 index of the array , for example , for 'tomato' it returns vegetable , but if I try it for the other vegetables , it returns unknown. If I remove that last statement

else{
 return false;
}

Then , cucumber becomes vegetable , but apple gots undefined? I'm a bit confused , so I'll be glad if someone explain me why this happens. Thank you.

Answer 1

You're doing a massive nested unnecessary for loop there. The task is pretty straightforward

The input comes as array of one string element, the name of the fruit. The output should be printed to the console.

You just have to grab that first inputArr value, which is a string and check if its value actually in your fruits, vegetables or else unknown.

Something like,

function fruitOrVegetable(inputArr) {
    var fruits = ['banana', 'apple', 'kiwi', 'cherry', 'lemon', 'grapes', 'peach'];
    var vegetables = ['tomato', 'cucumber', 'pepper', 'onion', 'garlic', 'parsley'];

    var val = inputArr[0];

    return fruits.indexOf(val) !== -1 ? 'fruit' : vegetables.indexOf(val) !== -1 ? 'vegetables' : 'unknown';
}

---

Edit:

Let's break the code above,

// This is to grab the string from the first value in `inputArr` and store in `val`.
var val = inputArr[0];

And returning,

¹ fruits.indexOf(val) !== -1 ? 'fruit' :

² vegetables.indexOf(val) !== -1 ? 'vegetables' :

³ 'unknown';

1. Check whether val exists in fruits, if it does, return 'fruit' or else run ²
2. Check whether val exists in vegetables, if it does, return 'vegetables' or else run ³
3. Return 'undefined'

This operation equals to,

if (fruits.indexOf(val) !== -1) {
    return 'fruit';
}
else if (vegetables.indexOf(val) !== -1) {
    return 'vegetables';
}
else {
    return 'unknown';
}

More info:

?: is a conditional (ternary) operator. (Read more here). It's pretty handy to evaluate expression

e.g.

var myval = 1;
console.log(myval ? 'true' : 'false'); // true

myval = false;
console.log(myval ? 'true' : 'false'); // false

indexOf is an array native function, which you can check the index of a value in an array. (Read more here)

e.g.

var myarr = ['test', 'tost', 'aww'];
console.log(myarr.indexOf('tost')); // returns 1
console.log(myarr.indexOf('tosts')); // returns -1 (value not found)