What is the best approach to add additional functionality to an already existing object method?

Let's say we have an obj,

var obj = {
     l:function(){
            alert(1);
     }
}

In what way can additional functionality be incorporated into obj.l without directly modifying the object?

Answer №1

Is it possible to make changes without editing the object directly?

If by not modifying the object you mean not altering its properties directly, then no, it is not possible. However, if you are referring to not making changes to the source code of the object itself, you can still add functionality at the beginning or end of the object, but not in the middle.

(function() {
    var original = obj.l;
    obj.l = function() {
       var retval;

       // You have the opportunity to perform actions here

       // Call the original method
       retVal = original.apply(this, arguments);

       // Additional operations can be executed here

       // Return the result
       return retVal;
    };
})();

The use of the scoping function ensures that the variable 'original' is accessible only within this block of code.

In the provided example, calling the original method will retain the same context ('this') and set of arguments passed to your custom wrapper function. It is also feasible to pass different arguments by utilizing 'Function#call' instead of 'Function#apply'.

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