Lodash对象按索引

Question

In lodash, how can I get an object from an array by the index at which it occurs, instead of searching for a key value.

var tv = [{id:1},{id:2}]
var data = //Desired result needs to be {id:2}

Answer 1

Let's take for example this collection:

var collection = [{id: 1, name: "Lorem"}, {id: 2, name: "Ipsum"}];

I will talk about two approaches, indexing and not indexing.

In general, indexing is better if you want to access many of the items, because you loop the collection once. If not, Meeseeks solution with find is the right choice.

Indexing

var byId   = _.groupBy(collection, 'id');
var byName = _.groupBy(collection, 'name');

now you can reach each item by it indexed key:

console.log(byId[2]);      // Object {id: 2, name: "Ipsum"}
console.log(byName.Lorem); // Object {id: 1, name: "Lorem"}

Without indexing

var item = _.find(collection, {id: 2});
console.log(item); // Object {id: 2, name: "Ipsum"}

Answer 2

I think what you're looking for is find

You can give it an object and it will return the matched element or undefined

Example

var arr = [ { id: 1, name: "Hello" }, { id: 2, name: "World" } ];

var data = _.find(arr, { id: 1 }); // => Object {id: 1, name: "Hello"}

var data = _.find(arr, { id: 3 }); // => undefined