Get array of property values from array of objects with jquery [duplicate]

Question

I am trying to get from here:

example = [{
  name: "someone1",
  city: "somewhere1",
  state: "someplace1"
},{
  name: "someone2",
  city: "somewhere2",
  state: "someplace2"
}]

to here:

example.name = [ "someone1", "someone2" ]

In as little a code as possible. Obviously I could just loop it and build the array but I need to do this a large number of times on a variety of objects. I could write a function to do it but it would be difficult to make the function general enough for my application.

Is there a shortcut for this in jQuery?

Answer 1

You can iterate through the object keys and save the name in the array using push:

example = [{
  name: "someone1",
  city: "somewhere1",
  state: "someplace1"
}, {
  name: "someone2",
  city: "somewhere2",
  state: "someplace2"
}];
var arrNames = [];
//iterate through object keys
Object.keys(example).forEach(function(key) {
  //get the value of name
  var val = example[key]["name"];
  //push the name string in the array
  arrNames.push(val);
});
console.log(arrNames);//prints ["someone1", "someone2"]

After @Felix suggestion(with which I agree) there is no need to use Object.keys:

example = [{
  name: "someone1",
  city: "somewhere1",
  state: "someplace1"
}, {
  name: "someone2",
  city: "somewhere2",
  state: "someplace2"
}];
var arrNames = [];
//iterate through object keys
example.forEach(function(item) {
  //get the value of name
  var val = item.name
  //push the name string in the array
  arrNames.push(val);
});
console.log(arrNames); //prints ["someone1", "someone2"]

References

Object.keys()

Array.prototype.forEach()

Array.prototype.push()

Answer 2

I made a quick test for you here: http://jsperf.com/jquery-vs-javascriptlvjsklvjsfklsfklsdjfk

It consists of three solutions:

A basic for loop

for (var i = 0; i < example.length; i++) {
    array.push(example[i].name);
}

A jQuery $.each()

$.each(example, function(i, item) {
    array.push(example[i].name);
});

And one answer posted to this thread

Object.keys(example).forEach(function(key) {
  //get the value of name
  var val = example[key]["name"];
  //push the name string in the array
  array.push(val);
});

Here are the results (bigger bar is better)

Basically what you have to keep in mind is that jQuery might have a shortcut which consists of "less code", but in reality it'll have worse performance than if you wrote the code yourself.

Answer 3

You can use the $.map function from jQuery :

var value = $.map(example, function () {
    return this.name;
});

This will return an array of the items.

Answer 4

Here is how to do it using jinqJs

The line of code is:

jinqJs().from(example).select(function(row){return row.name;});

var example = [{
  name: "someone1",
  city: "somewhere1",
  state: "someplace1"
},{
  name: "someone2",
  city: "somewhere2",
  state: "someplace2"
}];

var result = jinqJs().from(example).select(function(row){return row.name;});

document.body.innerHTML = '<pre>' + JSON.stringify(result, null, 2) + '</pre><br><br>';

<script src="https://rawgit.com/fordth/jinqJs/master/jinqjs.min.js"></script>

Answer 5

This is the simplest solution I can think of:

function doThat (myArray) {
  newObject = {};
  myArray.forEach(function (obj, idx) {
    var keys = Object.keys(obj);
    keys.forEach(function (key) {
      if (!obj[key]) {
        newObject[key] = [];
      }
      newObject[key][idx] = obj[key]; 
    });
  });
  return newObject;
}