1var users = [
2  { 'user': 'barney', 'age': 36, 'active': true },
3  { 'user': 'fred',   'age': 40, 'active': false }
4];
5 
6_.filter(users, function(o) { return !o.active; });
7// => objects for ['fred']
8 
9// The `_.matches` iteratee shorthand.
10_.filter(users, { 'age': 36, 'active': true });
11// => objects for ['barney']
12 
13// The `_.matchesProperty` iteratee shorthand.
14_.filter(users, ['active', false]);
15// => objects for ['fred']
16 
17// The `_.property` iteratee shorthand.
18_.filter(users, 'active');
19// => objects for ['barney']

1const arr = [
2  {},
3  { hello: null },
4  { hello: false },
5  { hello: 0 },
6  { hello: 'world' }
7];
8
9_.filter(arr, 'hello'); // [{ hello: 'world' }]

1const _quote_filter = _.map(quote_state, (val, key) => {   if (val) {      return key   }})console.log(_quote_filter) //=> [ 'btc', undefined, undefined ]