Mixing
Implementing Stream in JavaScript
I want to implement a stream object that can do this:
// a -------1------2----3
// map ---------------
// b --------2------4----6
const a = new Stream();
const b = a.map(value => value * 2);
b.subscribe(console.log);
a.push(1);
// 2
a.push(2);
// 4
a.push(3);
// 6
The idea here is that the object b can subscribe new callbacks to stream a. The map function should listen when push is called and apply the mapped out function as well as the originally subscribed one. This is the implementation I have so far:
class Stream {
constructor(queue = ) {
this.queue = queue;
}
subscribe(action) {
if (typeof action === 'function') {
this.queue.push(action);
}
}
map(callback) {
this.queue = this.queue.map(
actionFn => arg => action(callback(arg))
);
return this;
}
push(value) {
this.queue.forEach(actionFn => {
actionFn.call(this, value);
});
}
}
The problem with current implementation is that originally the queue in class Stream is empty so it doesn't go through it. Would appreciate any suggestions or help. I would like to not use any library for this.
javascript node.js stream
asked Nov 20 '18 at 5:33
DalerDaler
636
add a comment |
I want to implement a stream object that can do this:
// a -------1------2----3
// map ---------------
// b --------2------4----6
const a = new Stream();
const b = a.map(value => value * 2);
b.subscribe(console.log);
a.push(1);
// 2
a.push(2);
// 4
a.push(3);
// 6
The idea here is that the object b can subscribe new callbacks to stream a. The map function should listen when push is called and apply the mapped out function as well as the originally subscribed one. This is the implementation I have so far:
class Stream {
constructor(queue = ) {
this.queue = queue;
}
subscribe(action) {
if (typeof action === 'function') {
this.queue.push(action);
}
}
map(callback) {
this.queue = this.queue.map(
actionFn => arg => action(callback(arg))
);
return this;
}
push(value) {
this.queue.forEach(actionFn => {
actionFn.call(this, value);
});
}
}
The problem with current implementation is that originally the queue in class Stream is empty so it doesn't go through it. Would appreciate any suggestions or help. I would like to not use any library for this.
javascript node.js stream
asked Nov 20 '18 at 5:33
DalerDaler
636
add a comment |
I want to implement a stream object that can do this:
// a -------1------2----3
// map ---------------
// b --------2------4----6
const a = new Stream();
const b = a.map(value => value * 2);
b.subscribe(console.log);
a.push(1);
// 2
a.push(2);
// 4
a.push(3);
// 6
The idea here is that the object b can subscribe new callbacks to stream a. The map function should listen when push is called and apply the mapped out function as well as the originally subscribed one. This is the implementation I have so far:
class Stream {
constructor(queue = ) {
this.queue = queue;
}
subscribe(action) {
if (typeof action === 'function') {
this.queue.push(action);
}
}
map(callback) {
this.queue = this.queue.map(
actionFn => arg => action(callback(arg))
);
return this;
}
push(value) {
this.queue.forEach(actionFn => {
actionFn.call(this, value);
});
}
}
The problem with current implementation is that originally the queue in class Stream is empty so it doesn't go through it. Would appreciate any suggestions or help. I would like to not use any library for this.
javascript node.js stream
asked Nov 20 '18 at 5:33
DalerDaler
636
I want to implement a stream object that can do this:
// a -------1------2----3
// map ---------------
// b --------2------4----6
const a = new Stream();
const b = a.map(value => value * 2);
b.subscribe(console.log);
a.push(1);
// 2
a.push(2);
// 4
a.push(3);
// 6
The idea here is that the object b can subscribe new callbacks to stream a. The map function should listen when push is called and apply the mapped out function as well as the originally subscribed one. This is the implementation I have so far:
class Stream {
constructor(queue = ) {
this.queue = queue;
}
subscribe(action) {
if (typeof action === 'function') {
this.queue.push(action);
}
}
map(callback) {
this.queue = this.queue.map(
actionFn => arg => action(callback(arg))
);
return this;
}
push(value) {
this.queue.forEach(actionFn => {
actionFn.call(this, value);
});
}
}
The problem with current implementation is that originally the queue in class Stream is empty so it doesn't go through it. Would appreciate any suggestions or help. I would like to not use any library for this.
javascript node.js stream
javascript node.js stream
asked Nov 20 '18 at 5:33
DalerDaler
636
asked Nov 20 '18 at 5:33
DalerDaler
636
edited Nov 20 '18 at 6:35
Daler
asked Nov 20 '18 at 5:33
DalerDaler
636
asked Nov 20 '18 at 5:33
DalerDaler
636
asked Nov 20 '18 at 5:33
DalerDaler
636
636
add a comment |
add a comment |
1 Answer
1
active
oldest
votes
Your map needs to create a new Transform stream and return it. Instead of the subscribe you could simply use the standard on('data') event or, better use the read method.
Lastly - you could simply use my work and have your map method already efficiently implemented by using scramjet, which does exactly what you shown above - and moreover it supports async functions. :)
Here's how you'd use it (in some getStream function):
const {DataStream} = require('scramjet');
const stream = new DataStream();
stream.write(1); // you can also use await stream.whenWrote(1);
stream.write(2);
stream.write(3);
return stream.map(x => x * 2);
and then read it somewhere else:
stream.on('data', x => console.log(`x: ${x}`));
// x: 2
// x: 4
// x: 6
Take a look at the scramjet docs here
answered Nov 26 '18 at 15:07
Michał KaprackiMichał Kapracki
854718
add a comment |
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1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
Your map needs to create a new Transform stream and return it. Instead of the subscribe you could simply use the standard on('data') event or, better use the read method.
Lastly - you could simply use my work and have your map method already efficiently implemented by using scramjet, which does exactly what you shown above - and moreover it supports async functions. :)
Here's how you'd use it (in some getStream function):
const {DataStream} = require('scramjet');
const stream = new DataStream();
stream.write(1); // you can also use await stream.whenWrote(1);
stream.write(2);
stream.write(3);
return stream.map(x => x * 2);
and then read it somewhere else:
stream.on('data', x => console.log(`x: ${x}`));
// x: 2
// x: 4
// x: 6
Take a look at the scramjet docs here
answered Nov 26 '18 at 15:07
Michał KaprackiMichał Kapracki
854718
add a comment |
Your map needs to create a new Transform stream and return it. Instead of the subscribe you could simply use the standard on('data') event or, better use the read method.
Lastly - you could simply use my work and have your map method already efficiently implemented by using scramjet, which does exactly what you shown above - and moreover it supports async functions. :)
Here's how you'd use it (in some getStream function):
const {DataStream} = require('scramjet');
const stream = new DataStream();
stream.write(1); // you can also use await stream.whenWrote(1);
stream.write(2);
stream.write(3);
return stream.map(x => x * 2);
and then read it somewhere else:
stream.on('data', x => console.log(`x: ${x}`));
// x: 2
// x: 4
// x: 6
Take a look at the scramjet docs here
answered Nov 26 '18 at 15:07
Michał KaprackiMichał Kapracki
854718
add a comment |
Your map needs to create a new Transform stream and return it. Instead of the subscribe you could simply use the standard on('data') event or, better use the read method.
Lastly - you could simply use my work and have your map method already efficiently implemented by using scramjet, which does exactly what you shown above - and moreover it supports async functions. :)
Here's how you'd use it (in some getStream function):
const {DataStream} = require('scramjet');
const stream = new DataStream();
stream.write(1); // you can also use await stream.whenWrote(1);
stream.write(2);
stream.write(3);
return stream.map(x => x * 2);
and then read it somewhere else:
stream.on('data', x => console.log(`x: ${x}`));
// x: 2
// x: 4
// x: 6
Take a look at the scramjet docs here
answered Nov 26 '18 at 15:07
Michał KaprackiMichał Kapracki
854718
Your map needs to create a new Transform stream and return it. Instead of the subscribe you could simply use the standard on('data') event or, better use the read method.
Lastly - you could simply use my work and have your map method already efficiently implemented by using scramjet, which does exactly what you shown above - and moreover it supports async functions. :)
Here's how you'd use it (in some getStream function):
const {DataStream} = require('scramjet');
const stream = new DataStream();
stream.write(1); // you can also use await stream.whenWrote(1);
stream.write(2);
stream.write(3);
return stream.map(x => x * 2);
and then read it somewhere else:
stream.on('data', x => console.log(`x: ${x}`));
// x: 2
// x: 4
// x: 6
Take a look at the scramjet docs here
answered Nov 26 '18 at 15:07
Michał KaprackiMichał Kapracki
854718
answered Nov 26 '18 at 15:07
Michał KaprackiMichał Kapracki
854718
answered Nov 26 '18 at 15:07
Michał KaprackiMichał Kapracki
854718
answered Nov 26 '18 at 15:07
Michał KaprackiMichał Kapracki
854718
854718
add a comment |
add a comment |
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