SYSK 337: JavaScript – Should You Define Functions Inside a Prototype or Outside?
Yesterday’s post described three ways to extend an existing type. It occurred to me that there is one more, slightly different mechanism, for defining a prototype function… you can think of it as Method 2-b.
Consider the following:
function TestClass(param1)
{
this._param1 = param1;
TestClass.prototype.get_param1 = function()
{
return this._param1;
}
}
If you were to break (while debugging the code) and look at the CallStack window, the get_param1 function would be seen as ‘JScript anonymous function’. While it may not be important if you break in the get_param1 function, it would certainly be a valuable piece of information if you’re debugging some code downstream called from get_param1.
To get the actual function name and not the ‘anonymous’, you can define it as follows:
function TestClass(param1)
{
this._param1 = param1;
}
function TestClass$get_param1()
{
return this._param1;
}
TestClass.prototype =
{
get_param1: TestClass$get_param1
}
In this case, you should see ‘TestClass$get_param1’ in the CallStack window…
It’s my understanding that Microsoft AJAX team defines functions inside a prototype for release versions of scripts to minimize script size, and outside a prototype to maximize debuggability in debug versions.
