Javascript delete object from object

Question

I have following function that should delete an object in object under following id:

contactDeleteCounter++;
console.log(orderContactIds);
console.log(deletePosition);
console.log(orderContactIds[deletePosition]);
delete orderContactIds.deletePosition;
console.log(orderContactIds.deletePosition);
console.log(orderContactIds);
console.log(deletePosition);

The problem is that i everything works great in Chrome, but Firebug in Firefoxshows me following output:

Object { 0={...}, 1={...}, 2={...}}
2
Object { id= "20" , type= "1" }
undefined
Object { 0={...}, 1={...}, 2={...}}
2

As you see, the attribute is undefined, but when i look in the object, it is still there...?

Answer 1

The answer is to create a callback and to make async Jquery:

function deleteCallback(deletePosition) {
 $.ajaxSetup({
 async : false
 });
 console.log(orderContactIds);
 console.log(deletePosition);
 console.log(orderContactIds[deletePosition]);
 delete orderContactIds[deletePosition];
 console.log(orderContactIds.deletePosition);
 console.log(orderContactIds);
 console.log(deletePosition);
 $.ajaxSetup({
 async : true
 });
}

Answer 2

The delete operator deletes only a reference, never an object itself. If it did delete the object itself, other remaining references would be dangling, like a C++ delete. (And accessing one of them would cause a crash. To make them all turn null would mean having extra work when deleting or extra memory for each object.)

Since Javascript is garbage collected, you don't need to delete objects themselves - they will be removed when there is no way to refer to them anymore.

It can be useful to delete references to an object if you are finished with them, because this gives the garbage collector more information about what is able to be reclaimed. If references remain to a large object, this can cause it to be unreclaimed - even if the rest of your program doesn't actually use that object.

• kussberg: orderContactIds is a global object, that i need all the time, how i can delete the object with ID=2? Not in the reference, but in the global value? NB!: This code works in Chrome btw!?
• David Fariña: if you really need to delete a method, property, object in an object, try making a new object converted to an array (if it works for you) and there you can manipulate the values a way better. Always use arrays instead of objects when you have to manipulate the content of the array. Since an array is nothing more than a js object, it still has a few methods you cant use on objects. Hope that helped...