Apparently, <script> tags are not loaded in a deterministic order on IE and Webkit-based browsers.

This page TRIES TO WORK AROUND THIS ISSUE by adding 100 <script> tags in series by waiting for the onload handler of the previous tag to fire. This is considerably slower than loading the tags in parallel, as demonstrated here and here.

Each <script> tag points to to scriptdeterminism.php?num=NNN, where each value of NNN is a number from 1 to 100. Each request should load a small amount of JavaScript that pushes its NNN value onto a global RESULTS array. A timeout is scheduled 20 seconds in the future to assert whether all 100 values have been loaded, in order.