Calling a javascript function to execute a logic with data I extracted from html

I'm getting some data from an html and I need to call a Javascript to generate a parameter with the data I got in html.

How do I call Javascript to execute its logic with extracted data within a class? Javascript is below. Note that the program is in .NET.

function gerarParametro(chlg) {

   var start = aux3.charCodeAt(0);
   var end = aux4.charCodeAt(0);
   var arr = new Array(aux5);
   var m = Math.pow(((end - start) + 1), aux5);

   for (var i = 0; i < n; i++)
       arr[i] = aux3;

   for (var i = 0; i < m - 1; i++) {
      for (var j = aux5 - 1; j >= 0; --j) {
         var t = arr[j].charCodeAt(0);
         t++; arr[j] = String.fromCharCode(t);
         if (arr[j].charCodeAt(0) <= end) {
            break;
         } else { 
            arr[j] = aux3; 
         } 
       }

       var chlg = arr.join("");
    }
}