使用 rxjs 或本机 javascript 从 json 中提取特定键

Question

Assume that you have a json object as response. eg

var items = [{
    title: 'sample 1',
    image: 'http://www.lorempixel.com/700/600/',
    description: 'lorem ipsum'
}, {
    title: 'sample 2',
    image: 'http://www.lorempixel.com/900/1200/',
    description: 'lorem ipsum'
}]

How to map the object in order to have only a result object like this:

[{
    image: 'http://www.lorempixel.com/700/600/',

}, {
    image: 'http://www.lorempixel.com/900/1200/',
}]

is there a clean way using rxjs operators? or simply js native?

I tried it using :

const source = from(items);
const result = source.pipe(
                    pluck('image')
                );
result.subscribe(val => console.log('new values ', val));

But it's not working. Is there a cleaner way?

Answer 1

With vanilla JS just map over the items and return objects with just that property:

 var items = [{ title: 'sample 1', image: 'http://www.lorempixel.com/700/600/', description: 'lorem ipsum' },{ title: 'sample 2', image: 'http://www.lorempixel.com/900/1200/', description: 'lorem ipsum' }]; const out = items.map(({image}) => ({ image })); console.log(out);

Answer 2

Using Rxjs 6+
It's works in rxjs like in Vanilla js. here is an example from www.learnrxjs.io :

// RxJS v6+
import { from } from 'rxjs';
import { map } from 'rxjs/operators';

//emit ({name: 'Joe', age: 30}, {name: 'Frank', age: 20},{name: 'Ryan', age: 50})
const source = from([
  { name: 'Joe', age: 30 },
  { name: 'Frank', age: 20 },
  { name: 'Ryan', age: 50 }
]);
//grab each persons name, could also use pluck for this scenario
const example = source.pipe(map(({ name }) => name));
//output: "Joe","Frank","Ryan"
const subscribe = example.subscribe(val => console.log(val));