[javascript] Is it possible to wait until all javascript files are loaded before executing javascript code?

Expanding a bit on @Eruant's answer,

$(window).on('load', function() {
    // your code here
});

Works very well with both async and defer while loading on scripts.

So you can import all scripts like this:

<script src="/js/script1.js" async defer></script>
<script src="/js/script2.js" async defer></script>
<script src="/js/script3.js" async defer></script>

Just make sure script1 doesn't call functions from script3 before $(window).on('load' ..., make sure to call them inside window load event.

More about async/defer here.