Filtering Javascript Object Using Array Of Keys

Basically, I have JavaScript array that looks like this: var keyFilters = ['key_1', 'key_2', 'key_3']; And I have an object that looks like this: myObject['key_1'] = 'Value 1'; my

Solution 1:

for (i in myObject) if (keyFilters.indexOf(i) < 0) delete myObject[i];

Solution 2:

Underscore.js has a pretty good implementation. https://github.com/jashkenas/underscore/blob/master/underscore.js#L1108

// Return a copy of the object only containing the whitelisted properties.
  _.pick = restArgs(function(obj, keys) {
    var result = {}, iteratee = keys[0];
    if (obj == null) return result;
    if (_.isFunction(iteratee)) {
      if (keys.length > 1) iteratee = optimizeCb(iteratee, keys[1]);
      keys = _.allKeys(obj);
    } else {
      iteratee = keyInObj;
      keys = flatten(keys, false, false);
      obj = Object(obj);
    }
    for (var i = 0, length = keys.length; i < length; i++) {
      var key = keys[i];
      var value = obj[key];
      if (iteratee(value, key, obj)) result[key] = value;
    }
    return result;
  });

Solution 3:

I know there is no map function for objects in JS, but there is one for arrays. Would it be best to use that or just write a single-off function for iterating over the array and then over the object, and push to a new object that only has the matching keys, or is there some slicker way?

True, but you can map an Object's keys:

Object.keys(myObject).map(key => {
  if (keyFilters.indexOf(key) === -1) {
    delete myObject[key];
  }
});

I hope this suits you!

Solution 4:

If you want to return a new object based on your data, then use this:

let keyFilters = ["key_1", "key_2", "key_3"];
let myObject = {};
myObject["key_1"] = "Value 1";
myObject["key_2"] = "Value 2";
myObject["key_random"] = "Value 2";

let newObject = Object.keys(myObject)
.filter((key) => keyFilters.includes(key))
.map((key) => {
  return {[key]: myObject[key]}
})
.reduce((a, b) =>Object.assign({}, a,b));

It:

1) filters only the keys (as an array) which are included

2) maps through them and creates new objects (as an array) of key-value pairs

3) reduces the mapped array to a single object

Solution 5:

Iterate over the Object's keys, then look for the key in your array using includes method, if it doesn't exist, then delete it.

var safe_keys = ["key_1", "key_2", "key_3"],
  obj = {
    'key_1': 'Value 1',
    'key_2': 'Value 2',
    'key_random': 'Value 2'
  };

for (let key ofObject.keys(obj))
  !safe_keys.includes(key) && delete obj[key];

console.log(obj);