CODEWITHSUNDEEP
javascript
Jake
Jake

Reputation: 11

Dictionaries: Return a list of the keys which are paired with that value

I'm defining a function that returns a list of the keys which are paired with that value in the dictionary.

I can get the first key to be printed, but it will not print the second one or beyond. I know I should put in a list but I can't figure out to get that working.

dict1 = {'cat' : 1, 'dog': 3, 'bird':4,'lizard':4,'hamster': 5 };

function keyList(dict, value) {

  for(x in dict)  

    if(dict[x] == value) 

    return x;
}

console.log(keyList(dict1, 4));

When I run the current program I just get bird. I want the code to return both bird and lizard.

Upvotes: 0

Views: 59

Answers (4)

Nick G
Nick G

Reputation: 1973

Just iterate through the keys and filter the ones out where its value doesn't equal your passed value. 

dict1 = {'cat' : 1, 'dog': 3, 'bird':4,'lizard':4,'hamster': 5 }
    
function keyList(dict, value) {    
    return Object.keys(dict).filter(x => dict[x] === value);
}
    
console.log(keyList(dict1, 4))

Upvotes: 4

SScotti
SScotti

Reputation: 2338

You could try something this. There may be a filter function that does something similar:

dict1 = {'cat' : 1, 'dog': 3, 'bird':4,'lizard':4,'hamster': 5 }

function getPropertiesByValue(object, value) {

Object.keys(object).forEach(key => {
  if (object[key] != value ) delete object[key];
});
return object;
}
alert(JSON.stringify(getPropertiesByValue(dict1, 4)));

Upvotes: 0

Tyler Roper
Tyler Roper

Reputation: 21672

You could use Object.keys() to get an object's keys as an array (e.g. ["cat", "dog", "bird", "lizard", "hamster"]).

Array.filter() then allows you to specify which items to keep.

In your case, you want to keep "Keys whose value is 4", hence obj[key] === value.

const dict1 = {'cat' : 1, 'dog': 3, 'bird':4,'lizard':4,'hamster': 5 };
const keyList = (obj, value) => Object.keys(obj).filter(key => obj[key] === value);

console.log( keyList(dict1,4) );

Upvotes: 1

imvain2
imvain2

Reputation: 15847

Instead of immediately returning, push the value to an array then return the array

dict1 = {'cat' : 1, 'dog': 3, 'bird':4,'lizard':4,'hamster': 5 }

function keyList(dict, value) {
    let keys = [];
    for(x in dict)
    if(dict[x] == value){keys.push(x);}
    return keys;
}

console.log(keyList(dict1, 4))

Upvotes: 1

Related Questions