I recently ran into a problem where my Javascript was looping, and constantly calling a function. As the browser was locking up, I found it very hard find out the cause of the issue. To help resolve this issue I wrote the following.
The comments explain how to use it. In short it records every entrance into a function and counts the instances and pops up an "alert" when a proc is called 50 times (the number is adjstable).
//
// You should place the following lines at the top of your page
//
// var functionCalls = new Array(); // used to record all the calls
// var consecutiveCallCount = 0; // used to check for consecutive calls
// var lastFunctionCalled = ''; // used to check for consecutive calls
// var consecutiveCallCountAlertThreshold = 50; // an alert is generated if a method is called this many times consecutively
//
// You should also put an empty DIV as show below, somewhere on the page. The
// contents of the div will be updated after every function call, and will
// highlight the through put of every function. If you have a serious loop
// this will not be updated until the consecutive threshold is reached.
//
//
//
// Place a call to this function at the top of every function that you want to track
// e.g...
// function someFoo () {
// storeFunctionCalls();
// ...
//
// This function will count every call to the function and display it to screen.
function storeFunctionCalls() {
// get the name of the function that called this one
var temp = arguments.callee.caller.toString();
var fName = temp.substring(temp.indexOf("function") + 8, temp.indexOf("(")) || "anoynmous";
fName = fName.replace(/^\s+|\s+$/g, '');
// loop through the existing method calls and update the count
var indexOfExistingRow = -1;
for (var i = 0; i < functionCalls.length; i++) {
if (functionCalls[i].Name == fName) {
functionCalls[i].Count++;
indexOfExistingRow = i;
break;
}
}
// the method that called this has not done so before so add it into the collection
if (indexOfExistingRow == -1) {
functionCalls.push({ "Name": fName, "Count":1 });
}
// update the onscreen display of method calls
var s = '';
for (var i = 0; i < functionCalls.length; i++) {
s += functionCalls[i].Name + ': ' + functionCalls[i].Count + '';
}
$('#debugOutput').html(s);
// checks for the consecutive calls and alert if we've passed the threshold.
if (fName == lastFunctionCalled) {
consecutiveCallCount++;
if (consecutiveCallCount == consecutiveCallCountAlertThreshold) {
alert(consecutiveCallCount + ' consecutive method calls to the same function :' + fName);
}
} else {
lastFunctionCalled = fName;
consecutiveCallCount = 0;
}
}
