Javascript "pop" from object

Properties in an object are not stored in a stack so the basic concept won't work reliably (aside from the other issues mentioned in the comments above).

If you really need such a construct try something like this.

var ObjectStack = function(obj) {
    this.object = obj;
    this.stack=[];
};
ObjectStack.prototype.push = function(key,value) {
    this.object[key]=value;
    this.stack.push(key);
};
ObjectStack.prototype.pop = function() {
    var key = this.stack.pop();
    var prop = this.object[key];
    delete this.object[key];
    return prop;
};

var my_obj = {};
var my_stack = new ObjectStack(my_obj);
my_stack.push("prop1",val1);
my_stack.push("prop2",val2);

var last_prop = my_stack.pop(); //val2

Demo: http://jsfiddle.net/a8Rf6/5/

for( key in profiles ){

You should really declare key as a var.

profiles[key] = 0;            // Save over property just in case "delete" actually deletes the property contents instead of just removing it from the object

is unnecessary. Delete doesn't touch the value of the property (or in the case of a property that has a setter but no getter, even require that it have a value).

If the object has any enumerable properties on its prototype, then this will do something odd. Consider

Object.prototype.foo = 42;

function take(obj) {
  for (var key in obj) {
    // Uncomment below to fix prototype problem.
    // if (!Object.hasOwnProperty.call(obj, key)) continue;
    var result = obj[key];
    // If the property can't be deleted fail with an error.
    if (!delete obj[key]) { throw new Error(); }
    return result;
  } 
}

var o = {};
alert(take(o));  // alerts 42
alert(take(o));  // still alerts 42

Having studied all the comments and solutions above, I can offer a completely ready solution based on them:

Object.prototype.pop = function() {
    for (var key in this) {
        if (!Object.hasOwnProperty.call(this, key)) continue;
        var result = this[key];
        if (!delete this[key]) throw new Error();
        return result;
    }
};

var obj = {
    a: '1',
    b: '2',
    c: '3'
};

console.log(obj.pop()); // 1
console.log(obj.pop()); // 2
console.log(obj.pop()); // 3
console.log(obj); // Object {  }

Perhaps someone will come in handy ; )

---

PS. If you use the code I propose along with the jQuery library, you may encounter errors in the console. In this case, the option given below is appropriate:

function _pop() {
    for (var key in this) {
        if (!Object.hasOwnProperty.call(this, key)) continue;
        if (key === 'pop') continue;
        var result = this[key];
        if (!delete this[key]) throw new Error();
        return result;
    }
}

var obj = {
    a: '1',
    b: '2',
    c: '3'
};

obj.pop = _pop;

console.log(obj.pop()); // 1
console.log(obj.pop()); // 2
console.log(obj.pop()); // 3
console.log(obj); // Object { pop: _pop() }

Nowadays you can simply use the spread operator with its Rest way:

const { key, ...profilesWithoutKey } = profiles;

Credit to this blog post