Export YouTube Watch Later to CSV

I wrote a JavaScript script to export YouTube’s Watch Later data to CSV, so I’ll share it a bit.

Feature: Save the video list from the Watch Later page as CSV in title,URL format.

Watch Later - YouTube

Bug: The order is random.

Usage: Go to the Watch Later page, open Chrome Developer Tools, and copy-paste the following source code. Note: You should wait a few seconds before executing just the last console.save(csv,'result.csv').

function getElementsByXPath(xpath, parent)
{
  let results = [];
  let query = document.evaluate(xpath,
      parent || document,
      null, XPathResult.ORDERED_NODE_SNAPSHOT_TYPE, null);
  for (let i=0, length=query.snapshotLength; i<length; ++i) {
    results.push(query.snapshotItem(i));
  }
  return results;
}

(function(console){

    console.save = function(data, filename){

        if(!data) {
            console.error('Console.save: No data')
            return;
        }

        if(!filename) filename = 'console.json'

        if(typeof data === "object"){
            data = JSON.stringify(data, undefined, 4)
        }

        var blob = new Blob([data], {type: 'text/json'}),
            e    = document.createEvent('MouseEvents'),
            a    = document.createElement('a')

        a.download = filename
        a.href = window.URL.createObjectURL(blob)
        a.dataset.downloadurl =  ['text/json', a.download, a.href].join(':')
        e.initMouseEvent('click', true, false, window, 0, 0, 0, 0, 0, false, false, false, false, 0, null)
        a.dispatchEvent(e)
    }
})(console)

var absolutePath = function(href) {
    var link = document.createElement("a");
    link.href = href;
    return link.href;
}

var xpath = '//*[@id="content"]/a' ;
var csv ;

for (i = 1; getElementsByXPath(xpath).length; i++) {
    text = getElementsByXPath('//*[@id="content"]/a/div/h3/span')[i].getAttribute("title");

    text = text.replace(/,/g, "、");
    text = '"' + text + '"'
    csv += text
    csv += ','
    // csv += "\n" ;

    text = getElementsByXPath(xpath)[i].getAttribute("href")
    text = absolutePath(text) ;

    text = text.replace(/,/g, "、");
    text = '"' + text + '"'
    csv += text
    // csv += ','
    csv += "\n" ;
}

console.save(csv,'result.csv')

This JavaScript program retrieves elements based on a specific XPath path on a web page, extracts data from those elements, and saves it to a CSV file. Here’s a step-by-step explanation of the program.

1. getElementsByXPath function:

   • A function that receives an XPath expression and parent element, and retrieves elements matching the specified XPath.
   • Uses document.evaluate to evaluate the XPath and retrieve matching elements.

2. (function(console){...})(console) part:

   • Code to extend the console.save function.
   • The console.save function adds a custom function for saving data to a file.

3. absolutePath function:

   • A function to convert relative URLs to absolute URLs.
   • Converts the given relative URL to an absolute URL using an <a> element and returns it.

4. xpath variable:

   • Specifies the XPath expression. This XPath expression is used to extract <a> elements on the page in a specific way.

5. csv variable:

   • A variable to store CSV data.

6. for loop:

   • Loops until getElementsByXPath(xpath).length. This condition loops until the number of elements becomes 0.

7. Processing inside the loop:

   • Uses getElementsByXPath('//*[@id="content"]/a/div/h3/span')[i].getAttribute("title") to get title text from the specified XPath.
   • The retrieved text data is added to the csv variable as a CSV cell separated by commas (,). The text data is enclosed in double quotes.
   • Uses getElementsByXPath(xpath)[i].getAttribute("href") to get the relative URL of the link from the element’s “href” attribute.
   • Converts the relative URL to an absolute URL using the absolutePath function, encloses it in double quotes, and adds it to the csv variable.
   • Separates cells with commas and adds a newline character (\n) at the end of the row.

8. console.save(csv, 'result.csv'):

   • Uses the console.save function to download the contents of the csv variable as a CSV file. The filename is ‘result.csv’. This function is custom-defined and serves the role of saving CSV data to a file.

This program retrieves titles and links from elements matching the specified XPath and saves them to a CSV file.