I have been trying to return a property of an object by filtering it first. Here's what I did:
var characters = [
{ 'name': 'barney', 'age': 36, 'blocked': false },
{ 'name': 'fred', 'age': 40, 'blocked': true },
{ 'name': 'pebbles', 'age': 1, 'blocked': false }
];
_.find(characters, function(chr) {
return chr.age == 40
});
It returns whole object where as I want to return specific property. Can anyone guide me how can I do it?
Any help will be appreciated.
You could use the Lodash chaining ability. As its name implies, it enables you to chain Lodash methods calls. _.filter and _.map are appropriate here:
const characters = [
{ 'name': 'barney', 'age': 36, 'blocked': false },
{ 'name': 'fred', 'age': 40, 'blocked': true },
{ 'name': 'pebbles', 'age': 1, 'blocked': false },
]
const names = _(characters)
.filter(c => c.age < 40)
.map('name')
.value()
alert(names)<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.3.0/lodash.min.js"></script>For the record, this is how you can do in pure JS:
const characters = [
{ 'name': 'barney', 'age': 36, 'blocked': false },
{ 'name': 'fred', 'age': 40, 'blocked': true },
{ 'name': 'pebbles', 'age': 1, 'blocked': false },
]
const names = characters
.filter(c => c.age < 40)
.map(c => c.name)
alert(names)
pluck isn't in lodash anymore :(
pluck is simply a map. This is actually even clearer with the ES6 arrow functions.
_.map also supports the _.property iteratee shorthand like _.map(characters, 'name')_.result(_.find(characters, function(obj) {
return obj.age === 40;
}), 'name');
var array = [{a: 1, b: 2}, {a: 3, b: 4}]
array.map(_.property('a')) // => [1, 3]
_.map short hand
var array = [{a: 1, b: 2}, {a: 3, b: 4}]
_.map(array, 'a') // => [1, 3]
As elclanrs mentioned in comment before obvious solution is just to access the property age after you filtered the object.
But if you wanted to be done in method, you can first extract all age values and then allpy find function on them:
var ageValues = _.pluck(characters, 'age'); //returns [36, 40, 1]
var resultAgeValue = _.find(ageValues, function(ageValue) {
return ageValue < 40
});
or, better looks in chain:
var resultAgeValue = _(characters).pluck('age').find(function(ageValue) {
return ageValue < 40
});
try jsFiddle: http://jsfiddle.net/pqr/j8rL780u/
find, not filter!filter.
ageafter you filtered the object you need.