In this chapter, we will consider a scenario where a photography competition is held and photographers need to upload photographs to the portal. The moment a photograph is uploaded, a thumbnail should be created immediately.

A function code is the main content that executes and performs some operations as shown as follows:

var Jimp = require("jimp"); 
 
// JavaScript function must export a single function via module.exports 
// To find the function and execute it 
 
module.exports = (context, myBlob) => { 
// context is a must have parameter and first parameter always 
// context is used to pass data to and from the function 
//context name is not fixed; it can be anything 
 
    // Read Photograph with Jimp 
    Jimp.read(myBlob).then((image) => { 
        // Manipulate Photograph  
      // resize the Photograph. Jimp.AUTO can be passed as one of the values. 
        image 
            .resize(200, 200)  
            .quality(40) 
            .getBuffer(Jimp.MIME_JPEG, (error, stream) => { 
                // Check for errors while processing the Photograph. 
                if (error) { 
               // To print the message on log console 
                    context.log('There was an error processing the Photograph.'); 
               // To communicate with the runtime that function is finished to avoid timeout 
                    context.done(error); 
                } 
                else { 
               // To print the message on log console 
                    context.log('Successfully processed the Photograph'); 
                    // To communicate with the runtime that function is finished to avoid timeout   
               // Bind the stream to the output binding to create a new blob 
                    context.done(null, stream); 
                } 
            }); 
    }); 
};