benchmarking tool

[jemminger]

sick of reinventing the wheel every time i wanted to benchmark some functions, so i wrote a simple tool:

function benchmark(fn, args, optionalDisplayName) {
	var output = document.getElementById("benchmark-output");

	//  set up the output textarea
	if (!output) {
		var container = document.createElement("div");
		container.setAttribute("id", "benchmark-container");

		var title = document.createElement("div");
		title.setAttribute("id", "benchmark-title");
		title.appendChild( document.createTextNode("benchmark results") );

		output = document.createElement("textarea");
		output.setAttribute("id", "benchmark-output");
		output.style.width = "100%";
		output.style.height = "15em";

		container.appendChild(title);
		container.appendChild(output);

		document.body.appendChild(container);
	}

	// make sure args is an Array
	if (args && args.constructor != Array) args = [args];
	
	var iStart = new Date().getTime();
	fn.apply(this, args);
	var iStop = new Date().getTime();

	var name = optionalDisplayName || /(.+)\n/.exec(fn.toString())[1];
	output.value += name + " : " + ((iStop-iStart)/1000) + " sec\n";
}

usage:
//  no args
function foo() {
  // do something
}

benchmark( foo );

//  with args
function bar1(arg) {
  // do something
}
function bar2(arg1, arg2, arg3) {
  // do something
}

benchmark( bar1, "something" );
benchmark( bar2, ["something", "2", "3"] );

//  using optional display name since functions defined
//  like below don't report a name
document.foobar = function(arg) {
  // do something
}

benchmark( document.foobar, "blah", "foobar()" );

-jeff

http://www.jeffemminger.com

try { succeed(); } catch(E) { tryAgain(); } finally { rtfm(); }
i like your sleeves...they're real big

 

[jemminger]

created faq216-6103


-jeff

http://www.jeffemminger.com

try { succeed(); } catch(E) { tryAgain(); } finally { rtfm(); }
i like your sleeves...they're real big

 

[LFI]

Jeff,

what's going on here:

fn.apply(this, args);

...and here:

/(.+)\n/.exec(fn.toString())[1]

?

Looks interesting! I've tried it in IE6 and Opera and it seems to work as expected.

Nice work!

--Dave


~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
O Time, Strength, Cash, and Patience!

 

[jemminger]

apply() is a method of Function objects that lets you apply an array of arguments. this way you can dynamically call a function and pass a variable number of arguments to it.

http://www.devguru.com/technologies/javascript/10692.asp

the line
/(.+)\n/.exec(fn.toString())[1]

is a regex to extract the first line up to a line break from the function definition; the [1] is to use only the first parenthesized capture

this allows us to extract "function foo()" for display in the output from a function like

function foo() {
  // do stuff
}

anonymous functions defined like

document.foobar = function() {
  // whatever
}

don't report their names (they're anonymous, duh ;-) )... hence the optionalDisplayName parameter

-jeff

http://www.jeffemminger.com

try { succeed(); } catch(E) { tryAgain(); } finally { rtfm(); }
i like your sleeves...they're real big