Does Robot Web Services read the HTML or Javascript instance code for subscribing to numeric values?

I only saw the c# read subscription code in the manual on web server, which is not for mobile. In addition, I get other values through HTML language for many times or cause the phenomenon of teacher trainer to get stuck. I want to know the change of value through subscription and then read it, but I did not find this method

Could you not look how it’s done in C# and just port the code to Javascript/HTML?

Thank you for your suggestion. I have studied the source file of C# about subscription code very hard yesterday, but my C# code is not good enough, so I had better not find a way to monitor the change of subscription variable.