patternjavascriptMinor

Video downloader app implemented in RxJs

Submitted by: @import:stackexchange-codereview·Mar 10, 2026·

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appimplementedvideodownloaderrxjs

Problem

I have used multiple map/flatmap combinations. Could anybody help me with the review?

var Rx = require('rx');
var RxNode = require('rx-node');
var request = require('request');
var _ = require('lodash');
var cheerio = require('cheerio');

exports.getResult = function(req, res) {
    var result = '';
    fetchContent({
            url: req.body.url
        }, req.body.season)
        .flatMap(getEpisodeRange)
        .map(formEpisodeUrl.bind(null, req.body.url, req.body.season))
        .flatMap(downloadHtml)
        .map(getGorillaUrl)
        .flatMap(postToGorilla)
        .map(getVideoUrl)
        .flatMap(prepareHtml)
        .subscribe(function(data) {
            result += data;
        }, function(error) {
            res.send(JSON.stringify(error))
        }, function() {
            res.send(result);
        });
}

function fetchContent(params) {
    console.log(params.url);
    var args = [].slice.call(arguments, 1)
    return Rx.Observable.create(function(observer) {
        request(params, function(error, response, body) {
            if (error) {
                observer.onError();
            } else {
                observer.onNext({
                    response: response,
                    body: body,
                    args: args
                });
            }
            observer.onCompleted();
        })
    });
};

function prepareHtml(url) {
    return

;
}

function fileName(url, season, episode) {
    return Rx.Observable.just(url.split('/'))
        .last().map(function(name) {
            return name.replace('_', ' ').concat(

S${season}E${episode}`);
});
}

function getVideoUrl(data) {
var pattern = /"http(.*)(\.flv|\.mkv|\.mp4)"/;
var matches = pattern.exec(data.body);
if (matches && matches[0]) {
return matches[0]
} else {
return null;
}
}

function postToGorilla(url) {
var params = {
url: url,
method: 'POST',
headers: {
'content-type': 'appli

Solution

Overall, I think this is very decent code, some observations:

JSHint

Use JsHint ;)

You have a number of missing semicolons, and an unnecessary semicolon

return url = new Buffer(url, 'base64').toString('ascii');

You are not using the function fileName(url, season, episode){ anywhere

Odd stuff

-
You use the extremely cool fetchContent({ url }); but also the mundane

{
  response: response,
  body: body,
  args: args
}

You should stick to 1 approach

Your regex /"http(.*)(\.flv|\.mkv|\.mp4)"/

Is not supporting avi, wmv, or mpg file extensions.

Is not supporting uppercase incoming file names extentions.

Keeps repeating the \. for each extension, so I would keep that out of the brackets.

If you plan for many entries, then I would keep the regex outside of the function, and generate that regex only 1 single time for performance

You have a stray console.log(params.url);, get rid of it

-
It seemed odd that the HTML you prepare has no text in the anchor:

return ``;

Also, do you want to consider at least surrounding the URL with double quotes?

Sugar

-
You use req.body 3 times in getResult, I would have had a var params = req.body; as a shortcut

-
This seems a good use case for a ternary:

if (matches && matches[0]) {
    return 
} else {
    return null;
}

could be

return (matches && matches[0]) ? matches[0] : null;

I am still not sure why you return null actually. PrepareHtml will return `

, so perhaps consider

return (matches && matches[0]) ? matches[0] : '';


Anonymous functions kill kittens every day

The 3 functions within your subscribe call are anonymous. It is in general terrible to look at a stack trace filled with anonymous functions

You also have one in getEpisodeRange




I do like that you declare your other functions 'the right way'



Comments go a long way

getEpisodeRange` needs comments, it is the most intense code

There are actually no comments at all in this code, and I can parse everything just fine except the above mentioned function

Style

Formatting looks good to me

Naming looks good to me

I did not find obvious repetitions from a DRY perspective

Code Snippets

{
  response: response,
  body: body,
  args: args
}

return `<a href=${url}></a>`;

if (matches && matches[0]) {
    return 
} else {
    return null;
}

return (matches && matches[0]) ? matches[0] : null;

return (matches && matches[0]) ? matches[0] : '';

Context

StackExchange Code Review Q#133812, answer score: 3

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