CODEWITHSUNDEEP
javascriptarraysjavascript-objects
learninghowtocode
learninghowtocode

Reputation: 83

Return a new object whose properties are those in the given object and whose keys are present in the given array.

:) I need to return a new object whose properties are those in the given object and whose keys are present in the given array.

code attempt:

var arr = ['a', 'c', 'e'];
var obj = {
  a: 1,
  b: 2,
  c: 3,
  d: 4
};

function select(arr, obj) {
 var result = {};
 var array = [];
 for (var key in obj){
   array.push(key);
 }
var num = arr.length + obj.length; 
    for (var i = 0; i < num; i++) {
     for(var j = 0; j < num; j++) {
       if (arr[i] === array[j]) {

       result.array[i] = obj.arr[i];
     }
     }
    }
    return result;
}

(incorrect) result:

{}

desired result:

// --> { a: 1, c: 3 }

Any advice? Thank you! :)

Upvotes: 1

Views: 766

Answers (2)

kind user
kind user

Reputation: 41893

Longer, but more readable version:

var arr = ['a', 'c', 'e'],
    obj = {a:1,b:2,c:3,d:4},
    hash = {};
    
arr.forEach(function(v){     //iterate over each element from arr
  Object.keys(obj).some(function(c){  //check if any key from obj is equal to iterated element from arr
    if (v == c) {
      hash[v] = obj[c]; //if it is equal, make a new key inside hash obj and assign it's value from obj to it
    }
  });
});

console.log(hash);

Short version:

var arr = ['a', 'c', 'e'],
    obj = {a:1,b:2,c:3,d:4},
    hash = {};
    
arr.forEach(v => Object.keys(obj).some(c => v == c ? hash[v] = obj[c] : null));

console.log(hash);

Upvotes: 2

Nina Scholz
Nina Scholz

Reputation: 386560

You could iterate the given keys, test if it is a key in the object and assign the value to the same key in the result object.

function select(arr, obj) {
    var result = {};
    arr.forEach(function (k) {
        if (k in obj) {
            result[k] = obj[k];
        }
    });
    return result;
}

var arr = ['a', 'c', 'e'],
    obj = { a: 1, b: 2, c: 3, d: 4 };

console.log(select(arr, obj));

Upvotes: 2

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