• Distribution:
  • Firebug (which is both a debugger and a profiler) is distributed as a Firefox plug-in
• Setting Up:
  • Downloading the plug-in will start the installation process (which you will need to "Allow")
  • You may need to re-start Firefox to complete the installation

1. Start Firefox
2. Start Firebug by clicking on in the toolbar
3. Select the Console tab
4. Select "All"
5. Start the profiling process by clicking on "Profile"
6. Load the HTML page containing the code to profile
7. Use the code
8. Stop the profiling process by clicking on "Profile" (which will generate the report)

• Retrieving the Scripts:
  • The "Net" tab in Firebug has a "JavaScript" filter that provides information about the time required to retrieve scripts
• XMLHttpRequest:
  • The "Net" tab in Firebug has an "XHR" filter that provides information about the time required to perform GET requests using XMLHttprequest
  • Example: The Slideshow App

Profiling a 1-Dimensional Optimization Algorithm

ecmascriptexamples/optimization/GoldenSection.js

/**
 * See if two floating point values are approximately equal
 *
 * @param a {number}   One value
 * @param b {number}   The other value
 * @return             true if a and b are approximately equal
 */
function equals(a, b)
{
   "use strict";   

   if (Math.abs(a-b) < 0.000001){return true;}
   return false;
}


/**
 * Return the midpoint between two floating point values
 *
 * @param a {number}   One value
 * @param b {number}   The other value
 * @return             The midpoint
 */
function midpoint(a, b)
{
   "use strict";   

   return (a+b)/2.0;   
}


/**
 * Minimize a "well-behaved" function of one variable using the Golden
 * Section algorithm. Note: If the solution is not be within the bounds
 * this function will iterate forever.
 *
 * @param  f   The function
 * @param  L_0 The lower bound of the search space
 * @param  U_0 The upper bound of the search space
 * @return The value of x that minimizes f (i.e., the argmin over [L_0, U_0])
 */
function argminGoldenSection(f, L_0, U_0)
{
   "use strict";   
   var L, t_L, t_R, U;

   // Initialize
   L = L_0;
   U = U_0;

   t_L = L + 0.382*(U - L);
   t_R = L + 0.618*(U - L);

   // Iterate
   while (!equals(L,U)){
      if (f(t_L) < f(t_R)){
//       L   = L;
         U   = t_R;
         t_R = t_L;
         t_L = L + 0.382*(U - L);
      }else{
         L   = t_L;
//       U   = U;
         t_L = t_R;
         t_R = L + 0.618*(U - L);
      }
  }

   return midpoint(L,U);
}


        

Profiling an n-Dimensional Optimization Algorithm