15

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?

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4
  • You have to use jquery loop. I hope this will help to you dear. stackoverflow.com/questions/2342371/… Commented Apr 6, 2015 at 13:55
  • 1
    Native javascript is always going to be faster than jQuery. Commented Apr 6, 2015 at 13:56
  • explain a bit more.. you have one object, that is an array of same objects and then..? Commented Apr 6, 2015 at 13:57
  • 3
    @DeftSoftInformatics No, one doesn't have to. Commented Apr 6, 2015 at 13:59

5 Answers 5

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13

You can use the $.map function from jQuery :

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

This will return an array of the items.

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2 Comments

This answer works but the one below was accepted because it can do all the property names I need at the same time. +1
adding parameter to the function worked for me: function (v) { return v.name; }
12

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()

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4 Comments

Just made a generic function of this taking the object name and key names and it works flawlessly. Great answer, thank you!
Object.keys(example).forEach(function(key) { is a very strange way to iterate over an array. Why not simply example.forEach(function(item) { ... })?
Thanks @FelixKling for the feedback. You are right. I will update my answer later.
How to get this to create an array of values like ["someone1", "somewhere1","someplace1"],[...] and so on?
8

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.

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2 Comments

Though forEach is the slowest, I'm not worried about speed and it allows me to do this for all properties I need with one loop (by not having return statements). Thank you for your input; I chose to use forEach as it is the fastest to write for my application.
This is the best answer to the question tho! You could improve the loop better by checking the length once at the begging and storing it as a local var rather than checking with each loop cycle. i.e. for (var i = 0, x = example.length; i < x; i++)
2

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>

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Comments

1

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;
}
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1 Comment

I think my solution is more generic since it keeps all the indexes as they were even if one of the objects in the array missed a property

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