Convert Array of Javascript Objects to single simple array

Question

I have not been able to figure out how to properly accomplish this.

I have a JS array of objects that looks like this:

[{"num":"09599","name":"KCC","id":null},{"num":"000027","name":"Johns","id":null}]

I would like to convert this into a simple, single JS array, without any of the keys, it should look like this:

[
  "09599",
  "KCC",
  "000027",
  "Johns" ]

The IDs can be dropped entirely. Any help would be really appreciated.

@op it is polite to show what you have tried so far in order to accomplish it, and explain why your attempts did not work for you. — Banana, Aug 10 '15 at 14:51
check out http://stackoverflow.com/questions/921789/how-to-loop-through-javascript-object-literal-with-objects-as-members for a generic strategy that could be applied to this problem — wolffer-east, Aug 10 '15 at 14:56

thefourtheye · Accepted Answer · 2015-08-10T15:07:58.813

4

Simply iterate the original array, pick the interesting keys and accumulate them in another array, like this

var keys = ['num', 'name'],
    result = [];

for (var i = 0; i < data.length; i += 1) {
  // Get the current object to be processed
  var currentObject = data[i];
  for (var j = 0; j < keys.length; j += 1) {
    // Get the current key to be picked from the object
    var currentKey = keys[j];
    // Get the value corresponding to the key from the object and
    // push it to the array
    result.push(currentObject[currentKey]);
  }
}
console.log(result);
// [ '09599', 'KCC', '000027', 'Johns' ]

Here, data is the original array in the question. keys is an array of keys which you like to extract from the objects.

If you want to do this purely with functional programming technique, then you can use Array.prototype.reduce, Array.prototype.concat and Array.prototype.map, like this

var keys = ['num', 'name'];

console.log(data.reduce(function (result, currentObject) {
  return result.concat(keys.map(function (currentKey) {
    return currentObject[currentKey];
  }));
}, []));
// [ '09599', 'KCC', '000027', 'Johns' ]

edited Aug 10 '15 at 15:07

answered Aug 10 '15 at 14:53

thefourtheye

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This is very specific. Wouldn't `Object.keys` make this solution far more generic. – Mouser Aug 10 '15 at 14:54
@Mouser OP didn't want the `id` to be extracted. – thefourtheye Aug 10 '15 at 14:54
2

I know, but a black list is better then a white list, with many keys? – Mouser Aug 10 '15 at 14:54
2

@Mouser It is subjective. What if the original object had 100 keys and OP wanted to get only 2 keys? – thefourtheye Aug 10 '15 at 14:56
@thefourtheye Thank you so much, it works perfectly. Additionally thank you for taking the time to explain everything! – WhyEnBe Aug 10 '15 at 14:57
Thought of that too. Perhaps for future viewers and to be complete add another version with a blacklist. – Mouser Aug 10 '15 at 14:57
@Mouser Hmmm, then we need to do lookup in the blacklist as well. – thefourtheye Aug 10 '15 at 15:01

score 0 · Answer 2 · answered Aug 10 '15 at 15:04

You can use Object.keys() and .forEach() method to iterate through your array of object, and use .map() to build your filtered array.

  var array = [{"num":"09599","name":"KCC","id":null},{"num":"000027","name":"Johns","id":null}];

  var filtered = array.map(function(elm){
    var tmp = [];
    //Loop over keys of object elm
    Object.keys(elm).forEach(function(value){
      //If key not equal to id
      value !== 'id'
      //Push element to temporary array
      ? tmp.push(elm[value])
      //otherwise, do nothing
      : false
    });
    //return our array
    return tmp;

  });

  //Flat our filtered array
  filtered = [].concat.apply([], filtered);

  console.log(filtered);
  //["09599", "KCC", "000027", "Johns"]

If we have to do it functional way, I have included a version in my answer. That would be better, I believe. — thefourtheye, Aug 10 '15 at 15:08

score 0 · Answer 3 · answered Aug 10 '15 at 15:07

How about using map :

var data =  [
              {"num":"09599","name":"KCC","id":null} 
              {"num":"000027","name":"Johns","id":null}
            ];

var result = data.map(function(obj) {
   return [
       obj.num,
       obj.name,
       obj.id
    ];
});

Convert Array of Javascript Objects to single simple array

3 Answers3