Create a basic implementation of a streams API. The user should be able to push values to a stream, and subscribe to values that are pushed to that stream.

For example,

const z = new Stream();
z.subscribe((value) = console.log(value));
z.subscribe((value) = console.log(value * 2));
z.subscribe((value) = console.log(value * 3));
z.push(2);

Should return
2
4
6

Question

Create a basic implementation of a streams API. The user should be able to push values to a stream, and subscribe to values that are pushed to that stream.

For example,

const z = new Stream();
z.subscribe((value) => console.log(value));
z.subscribe((value) => console.log(value * 2));
z.subscribe((value) => console.log(value * 3));
z.push(2);

Should return
2
4
6

Using Function · Accepted Answer

Dana Harris · Answer

class Stream {
	constructor() {
  	// cache incoming values
  	this.cache = [];
  }
  
  subscribe(fn) {
  	this.cache.push(fn);
  }
  
  push(val) {
  	// Use arrow function to get ref to access to class this.
  	this.cache.forEach((item) => {
    	item.call(this, val);
    })
  }
}

const stream = new Stream();
stream.subscribe((value) => console.log(value));
stream.subscribe((value) => console.log(value * 2));
stream.subscribe((value) => console.log(value * 3));
stream.push(2);

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