How to create an array of objects based on another array of objects?

Question

I have this array:

var arr1 = [
 {"user":"dan","liked":"yes","age":"22"},
 {"user":"sarah","liked":"no","age":"21"},
 {"user":"john","liked":"yes","age":"23"},
];

I would like to create a new (auxiliary) array of this array containing only users.

so that it looks like this:

var arr2 = [
 {"dan":"yes"},
 {"sarah":"no"},
 {"john":"yes"},
];

I tried:

var arr2 =[];
for(var i in arr1){
  arr2.push({[i[user]]:i[liked]});
}

Does he need tuning, ideas?

Answer 1

Use array.map

var arr1 = [
 {"user":"dan","liked":"yes","age":"22"},
 {"user":"sarah","liked":"no","age":"21"},
 {"user":"john","liked":"yes","age":"23"},
];

var arr2 = arr1.map(v => ({ user: v.user, liked: v.liked }));

console.log(arr2);

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With your update, although this can be done using array.map, I recommend using the structure of a key-value pair of values ​​instead. You will need it array.reduce.

  var arr1 = [
   {"user":"dan","liked":"yes","age":"22"},
   {"user":"sarah","liked":"no","age":"21"},
   {"user":"john","liked":"yes","age":"23"},
  ];

  var arr2 = arr1.reduce((c, v) => (c[v.user] = v.liked, c) , {});

  console.log(arr2);

Run codeHide result

Answer 2

Based on your edit:

arr1 = arr1.map(function(item){
  return{
    [item.user]: item.liked
  }
});

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Answer 3

var arr1 = [
 {"user":"dan","liked":"yes","age":"22"},
 {"user":"sarah","liked":"no","age":"21"},
 {"user":"john","liked":"yes","age":"23"},
];

var res = arr1.map(function(o) {
  var r = {};
  r[o.user] = o.liked;
  return r;
});

console.log(res);

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ECMAScript:

var arr1 = [
 {"user":"dan","liked":"yes","age":"22"},
 {"user":"sarah","liked":"no","age":"21"},
 {"user":"john","liked":"yes","age":"23"},
];

var res = arr1.map(o => ( { [o.user]: o.liked } ));

console.log(res);

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Answer 4

var arr2 =[];
for(var i in arr1){
    var obj= {};
    obj[arr1[i]['user']] = arr1[i]['liked'];
    arr2.push(obj)
} 

Answer 5

var arr2=[];
arr1.forEach(function(obj)
{
    var temp=new Object();
    temp[obj.user]=obj.liked;
    arr2.push(temp);
});

, ,

Answer 6

.

var array1 = [{ user: "dan", liked: "yes", age: "22" }, { user: "sarah", liked: "no", age: "21" }, { user: "john", liked: "yes", age: "23" }],
    array2 = array1.map(({ user, liked }) => ({ [user]: liked }));

console.log(array2);

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ES5

var array1 = [{ user: "dan", liked: "yes", age: "22" }, { user: "sarah", liked: "no", age: "21" }, { user: "john", liked: "yes", age: "23" }],
    array2 = array1.map(function (o) {
        var temp = {};
        temp[o.user] = o.liked;
        return temp;
    });

console.log(array2);

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