Error handling in JavaScript

One way to handle error in JavaScript is to use simple try-catch block.

function foo(flag)
{
    try
    {
        //Your code
    }
    catch(exception)
    {
        //Log exception in error log using exception object
    }
} 

In the above approach we have to write try-catch in all required functions.

Second approach is to register a function on window object which will get called always. It is similar to Page_Error function implementation in ASP.Net.

//Register handleError function to handles all browser error messages 
window.onerror = handleError;

//Function to handle all errors.
function handleError(exception) 
{
    //Perform log operation
    return true;
}

References :
JavaScript Error Handling

Error Handling

Error handling in javascript