CODEWITHSUNDEEP
javascript
Abhinav
Abhinav

Reputation: 8168

Return numeric Zero from a javascript function

There is a function that returns key of an object based on some condition, if the key it is returning is 0, then the value I get is undefined

var obj = {'some','values'};

function getObjectKey(){

   obj.forEach(function(value, key) {
      if(some condition){
         return key;
       }
    });

}

var objectKey = getObjectKey();
console.log(objectKey); //returns `undefined` if the key returned is 0.

How can I get the key if the key is 0?

Upvotes: 1

Views: 810

Answers (3)

pid
pid

Reputation: 11607

You need to specify keys in the object.

This is not valid syntax:

{'some','values'};

This would be an array:

[ 'some','values' ];

But you really want an object, so put in the keys:

 { "key0": "some", "key1": "values" };

Upvotes: 0

Nina Scholz
Nina Scholz

Reputation: 386868

You need another methode, because Array#forEach does not have a short circuit for ending the loop.

In this case, use better Array#some.

function getObjectKey(object, condition){
    var k;

    Object.keys(object).some(function(key) {
        if (condition(object[key])) {
            k = key;
            return true;
        }
    });
    return k;
}

var object = { zero: 0, one: 1, two: 2, three: 3, four: 4, five: 5 };

console.log(getObjectKey(object, function (v) { return v === 3; }));

With ES6, you could use Array#find

The find() method returns a value in the array, if an element in the array satisfies the provided testing function. Otherwise undefined is returned.

function getObjectKey(object, condition) {
    return Object.keys(object).find(function(key) {
        return condition(object[key]);
    });
}

var object = { zero: 0, one: 1, two: 2, three: 3, four: 4, five: 5 };

console.log(getObjectKey(object, v => v === 3));

Upvotes: 1

synthet1c
synthet1c

Reputation: 6282

// there was a syntax error with your obj
var obj = {
  'some': 'values', 
  'another': 'anotherValue',
  'zero': 0,
  'null': null
}

// you should take the object and the key with the function
function getObjectKey(obj, key){
  var keys = Object.keys(obj)
  var index = keys.indexOf(key)
  // if the bitshifted index is truthy return the key else return undefined
  return ~index
    ? obj[keys[index]]
    : void 0 // void value - will change the value given to it to undefined
}


console.log(getObjectKey(obj, 'some'))
console.log(getObjectKey(obj, 'another'))
console.log(getObjectKey(obj, 'doesntExist'))
console.log(getObjectKey(obj, 'zero'))
console.log(getObjectKey(obj, 'null'))

Upvotes: 0

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