Adding elements to an object in a loop

Question

I am trying to add elements to an object in a loop, but the output is unexpected.

I have tried 2 different ways that I have found on SO but neither have worked to the output I need.

request(options, (err, response, body) => {
  if (err) {
    reject(err);
  }
  var data = {};
  var res = JSON.parse(body);

  for (i = 0; i < res.teams.length; i++) {
    data[i] = { name: res.teams[i].name, id: res.teams[i].id };
  }
  console.log(data.name);

The problem with this is it outputs: '0': { name: 'test', id: 1 }. The '0' at the beginning is problematic. The other way I have tried is simply:

request(options, (err, response, body) => {
  if (err) {
    reject(err);
  }
  var data = {};
  var res = JSON.parse(body);

  for (i = 0; i < res.teams.length; i++) {
    data += { name: res.teams[i].name, id: res.teams[i].id };
  }
  console.log(data.name);

The problem with this is it displays [object, Object] 20 times.

I am trying to just get an output of my object like:

{ { name: 'test1', id: 1 },
  { name: 'test2', id: 2 },
}

Sounds like you want an array of objects. In which case start with an empty array and push each object onto it — Robin Zigmond
– Robin Zigmond, Commented Aug 27, 2019 at 18:15

Aaron Meese · Accepted Answer · 2019-08-27 18:29:42Z

1

What I would suggest is an array filled with objects. What you are trying to do right now is not valid. Here's an example of the proper formatting:

[ { name: 'test1', id: 1 },
  { name: 'test2', id: 2 },
]

This is how I would refactor your code:

var data = [];
var res = JSON.parse(body);

for (i = 0; i < res.teams.length; i++) {
    data.push({ name: res.teams[i].name, id: res.teams[i].id });
}
console.log(data);

This way you will have to loop over the array to access each object, such as getting { name: 'test1', id: 1 } by accessing data[0].

answered Aug 27, 2019 at 18:29

Aaron Meese

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Caio Saldanha · Accepted Answer · 2019-08-27 18:33:57Z

That would solve your problem, try this on js fiddle:

  //Assuming the response body:
  // {
  //		teams: [{id: 1, name: 'one'}, {id: 2, name: 'two'}],
  //    otherField: 'something here'
	// }
  var data = {};
  // Assuming response string is already parsed
  var res = {
  	teams: [{id: 1, name: 'one'}, {id: 2, name: 'two'}],
    otherField: 'something here'
  };

	res.teams.forEach((element, index, originalArray) => {
  	data = {
    // destructuring assignment. See: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Destructuring_assignment
			...data,
      // Define field using braces
      ['team'+index]: element
    };
  });
  
  // Now lets show all of them. Using map() just to show you a new method
  Object.keys(data).map((element, index) => {
  	console.log(data[element].name);
  });

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