Question which variable saves the loading progress of webgl?

Hi,
You can access the loading progress using the progress callback given to the UnityLoader in Javascript.
You can create a custom template to modify the "index.html" to hook into that callback https://docs.unity3d.com/Manual/webgl-templates.html

Code (JavaScript):

1. createUnityInstance(canvas, config, (progress) => {
2.      // Do something with progress variable here
3.      // progress is within range [0,1]
4.      progressBarFull.style.width = 100 * progress + "%";   }).then((unityInstance) => {
5.       loadingBar.style.display = "none";
6. }).catch((message) => {
7.       alert(message);
8. });