Adding external script files to your HTML document is simple that you could do it in your sleep. But this is not as trivial as you think. Where and how you add your script file majorly influences the performance of your website.

In this post, we will go through the techniques to include external script files to your HTML and look at how this can affect the performance.
We will compare which technique is preferable and efficient over others in varying situations.

• This blog post assumes you are familiar with basic HTML, CSS and JavaScript syntax.
• We will also learn about the attributes: async and defer.