Tanzim Saqib on .NET discovery

It's not pretty common. But, if you ever encounter such code, be sure it's a very bad practice. Introducing more scopes is a performance issue for JavaScript interpreter. It adds a new scope in the ladder. See the following sample scope:

function pageLoad()
{
    scope1();
    function scope1()
    {
        alert('scope1');
        scope2();
        
        function scope2()
        {
            alert('scope2');
        }
    }
}    

Introducing more scopes enforces the interpreter to go through new more sections in the scope chain that it maintains for code execution. So, unnecessary scopes reduce performance and it's a bad design too.

Avoid implementing your own getElementById method that will cause script to DOM marshalling overhead. Each time you traverse the DOM and look for certain HTML element requires the JavaScript interpreter to marshalling script to DOM. It's always better to use getElementById of document object. So, before you write a function, make sure similar functionality can be achieved from some other built-in functions.