How jQuery's $.extend function works, a way for object to inherit other objects properties and functions

object_inheritance_function.js

function extend(target_object) {
    // Look for additional parameters in this function
    // eg. extend(target_object, ....a,b,c,d)
    if (!arguments[1]) {
        return;
    }

    // If any extra arguments, which are objects
    // loop through them
    for (var index = 1; index < arguments.length; index++) {
        // get the object
        var object = arguments[index];

        for (var prop in object) {
            // Make sure the object property does not exist in the target_object object
            // Also that the property is the objects own property and not the default ones
            // inherited through JavaScript itself
            if (!target_object[prop] && object.hasOwnProperty(prop)) {
                // now pass the properties
                target_object[prop] = object[prop]
            }
        }
    }
}