Write file to disk from blob in electron application

I am creating an Electron Application in which I am recording data from webcam and desktop, at the end of the recording session, I want to save the data to a file in the background. I do not know how to write the data from a blob to a file directly. Any suggestions? Below is my current handling for MediaRecord Stop event.

this.mediaRecorder.onstop = (e) => {                                      
       var blob = new Blob(this.chunks,                                      
                           { 'type' : 'video/mp4; codecs=H.264' });                                                       
       var fs = require('fs');                                               
       var fr = new FileReader();                                            
       var data = null;                                                      
       fr.onload = () => {                                                   
           data = fr.result;                                                 
           fs.writeFile("test.mp4", data, err => {                           
               if(err) {                                                     
                   return console.log(err);                                  
               }                                                             
               console.log("The file was saved!");                           
           });                                                               
       };                                                                    
       fr.readAsArrayBuffer(blob);                                           
   }                          

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