Filtering object properties based on value

Question

Is there some elegant way of filtering out falsey properties from this object with lodash/underscore? Similar to how _.compact(array) removes falsey elements fr

Answer 1

Another approach

const objFilter = (obj, condition) => {
    let newObj = {}
    for (const [key, value] of Object.entries(obj)) {
        if (condition(value)) {
            newObj = { ...newObj, [key]: value }
        }
    }
    return newObj
}

Fire like this:

const newData = objFilter(oldData, (value) => value.marked === false)

Answer 2

Unfortunately I cannot direclty comment on the posts above yet, so I create this extra post.

Since Lodash v4 the functionality described above has been moved to _.pickBy. With _.identity as default you could also change your code to:

var filtered = _.pickBy(obj);

See this JSBin for a working example.

Answer 3

let temp = {
  propA: true,
  propB: true,
  propC: false,
  propD: true,
}

let obj = {}
for(x in temp){
   if(temp[x] == true){
     obj[x] = temp[x]
   }
}

console.log(obj)

Using for-in loop we can achieve it something like this.

Answer 4

From lodash 4, we can use pickBy() to get only the value equal to true.

const active = _.keys(_.pickBy(object));

Answer 5

Here are two vanilla javascript options:

A.: Iterate over the object's keys and delete those having a falsey value.

var obj = {
  propA: true,
  propB: true,
  propC: false,
  propD: true,
};

Object.keys(obj).forEach(key => {
  if (!obj[key]) delete obj[key];
});

console.log(obj);

_{See Object.keys() and Array.prototype.forEach()}

B.: Iterate over the object's keys and add truthy values to a new object.

var obj = {
  propA: true,
  propB: true,
  propC: false,
  propD: true,
};

var filteredObj = Object.keys(obj).reduce((p, c) => {    
  if (obj[c]) p[c] = obj[c];
  return p;
}, {});

console.log(filteredObj);

_{See Object.keys() and Array.prototype.reduce()}

Answer 6

Prior to Lodash 4.0

You want _.pick, it takes a function as an argument and returns an object only containing the keys for which that function returns truthy. So you can do:

filtered = _.pick(obj, function(value, key) {return value;})

Or even more succinctly:

filtered = _.pick(obj, _.identity)

Lodash 4.0

Lodash 4.0 split the _.pick function into _.pick, which takes an array of properties, and _.pickBy which takes a function. So now it'd be

filtered = _.pickBy(obj, function(value, key) {return value;})

Or, since _.pickBy defaults to using _.identity as it's second argument, it can just be written as:

filtered = _.pickBy(obj);