How to get it done with asynchronous file loading?

Hi there,

Thanks for the heads up James Barrett.

You'd have to implement some sort of queue to handle the asynchronous IO. For example, if we had a header.txt file, a content.txt file and a footer.txt file and did some code like this.

fs.readFile('header.txt', function(err, headerContent) {
   response.write(headerContent)
});


fs.readFile('content.txt', function(err, mainContent) {
   response.write(mainContent)
});

fs.readFile('footer.txt', function(err, footerContent) {
   response.write(footerContent)
});

The out put may look like...

Footer
Header
Content

Or...

Header
Footer
Content

Or any number of combinations.

You'd have to look at your template string and look for all instances of the things you want to replace and keep track of what you have done so far and then stream the string as you build it.

Using sync removes a lot of complexity in our code. I assume backend libraries like Express and Pug have a lot more complexity that would handle multiple file IO in an asynchronous fashion. This would've been a significant detour in the course. The goal was to see the general principles that would give you a sense of how frameworks and libraries work because they do all the heavy lifting and optimization for you.