dynamically check if function doesn't exist in object class

Question

I'm trying to create a jQuery style object class.

function obj(id){
    if (this.__proto__.constructor !== obj) {
        return new obj(id);
    }
    this.element = document.getElementById(id);

    this.remove = function(){
        this.element.parentNode.removeChild(this.element);
    }
    this.offset = function(){
        return this.element.getBoundingClientRect();
    }
}
obj(id).offset() // defined
obj(id).removeChild() //undefined
obj(id).appendChild() // undefined
obj(id).remove() // undefined

I got a problem. jQuery object can also use as a Javascript DOM object like $('#someid').innerHTML, but my object. I'm thinking about a solution that dynamically checks if a method does not exist in this object class, then return a DOM object return this.element.

How could I do this? Or any better ideas?

Not sure what you mean by "jQuery style object class", but a jQuery object can't be used as a DOM object like $("#someid").innerHTML. — cookie monster
– cookie monster, Commented May 24, 2014 at 7:53
You're mistaken: jQuery cannot chain DOM methods to jQuery objects ($('#someid').innerHTML is a syntax error). — David Thomas
– David Thomas, Commented May 24, 2014 at 7:53
"jQuery object can also use as a Javascript DOM object like $('#someid').innerHTML" No, it can't. innerHTML there would also be undefined. jQuery objects are wrappers around sets of elements. You could do $('#someid')[0].innerHTML (note the accessor). — T.J. Crowder
– T.J. Crowder, Commented May 24, 2014 at 7:54
The only way AFAIK to accomplish what you describe would be to use Proxy, which isn't available in most browsers yet since it's part of the next ECMAScript standard, which isn't finalized. — cookie monster
– cookie monster, Commented May 24, 2014 at 7:54

T.J. Crowder · Accepted Answer · 2014-05-24 07:55:13Z

jQuery object can also use as a Javascript DOM object like $('#someid').innerHTML

No, it can't. innerHTML there would also be undefined. jQuery objects are wrappers around sets of elements. You could do $('#someid')[0].innerHTML (note the accessor, [0]).

...checks if a method does not exist in this object class...

If you want to test for the existence of a function, you can use typeof:

if (typeof obj.method === "function")

Note that for certain host-provided functions on some older browsers, you may get "object" instead of "function", so you have to allow for that.

But you'd have to do that where you're using the function.

I'm thinking about a solution that dynamically checks if a method does not exist in this object class, then return a DOM object return this.element.

This is a bad idea. Instead, provide a means of accessing the underlying element (the way jQuery does). It will be possible with ES6's proxies, but those aren't available widely yet.

Collectives™ on Stack Overflow

dynamically check if function doesn't exist in object class

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related