Asynchronous document.write (ADW) is a JavaScript library that enables the usage of document.write in asynchronous scripts. After loading ADW, document.write may be called by any script even after the page has completed loading. ADW is backwards compatible with normal document.write and it also implements an asynchronous document.writeln method.

ADW can be utilized by providers of HTML "emebedding" scripts to enable the scripts to be included asynchronously (a la <script async>) when ADW is loaded. All you have to do is add eval(document.write.START); to the start of the code and eval(document.write.END); to the end. If the target page does not have ADW loaded, your code will behave as it would normally.

eval(document.write.START);
document.write(...);
eval(document.write.END);

Please note that ADW does not support inline scripts.