jQuery breaking "this" in constructor?

I'm working with jQuery and creating some OOP Javascript functionality. The object and its constructor has the following structure:

var zoomin = new Object();
zoomin = function() { // This is my constructor
    开发者_运维百科this.someFunction();
};

zoomin.prototype = {
    someFunction: function() {
        // More code here
    }
};

When I create an instance of zoomin (e.g. var my_zoom = new zoomin();), the call to this.someFunction() in the constructor does not work. It seems like jQuery is taking possession of "this" and this is why it is breaking.

I would really appreciate any help on how to get this to work properly.

Thanks!

Your class definition should be like this:

function zoomin() {    // This is my constructor
   this.someFunction();
};

For the member method definition, it should be:

zoomin.prototype.someFunction = function() {
     // More code here
};

or:

$.extend(zoomin.prototype, {
   someFunction : function() {
      // More code here
   }
});

Hope this helps. Cheers

your code is pretty messed up. you're creating a new Object, then assigning function to the same variable. so the first statement is not necessary (and not a good practice), then assigning object (with some properties) to the prototype of the zoomin object, instead of adding a property (someFunction) to it.

try to define your constructor like this:

function zoomin(){
// this is your constructor
}
zoomin.prototype.someFunction = function(){
// this is your method.
}

var zm = new zoomin();
zm.someFunction();

See the other answers as to cleaner ways to organize this. This answer just tries to address the notion of "jQuerying breaking 'this' in constructor".

A function-object (e.g. zoomin) must be invoked with new to act as a Constructor (constructors are just functions, there is nothing special without new). That is, if zoomin is used as a callback function in jQuery then this will be a particular (but arbitrary) object which is likely not a new object instance. This could give the illusion that jQuery breaks the constructor; however, it does not, because the constructor was not invoked with new and thus acts like a "normal function".

If using new fnObject then this (inside the fnOjbect function) will always be a new "fnObject" instance. There is no way for jQuery to change this, even if it tried really, really hard.

Also, the zoomin = new Object is 100% useless because the next line just assigns a new value (the constructor function-object) to zoomin :-)

Happy coding.