Question

Scenario:
– fill object1
– copying the content of object1 to object2
– delete element from object1

Result now:
– both object1 and object2 have 1 element deleted…?!

Wished result:
– object1 should have 1 element less than object2

The code:

var object1 = new Object();
object1['key_one']   = 'value_1';
object1['key_two']   = 'value_2';
object1['key_three'] = 'value_3';
object1['key_four']  = 'value_4';
var object2 = new Object();
object2 = object1;
delete object1['key_three'];

What am I doing wrong?

Answer 1

Your code does not do any copying. object2 is simply a new, empty object. Try this:

var object1 = {
  key_one: "value_1",
  key_two: "value_2",
  key_three: "value_3",
  key_four: "value_4"
};
var object2 = {};
for (var prop in object1) {
  object2[prop] = object1[prop];
}
delete object1["key_three"];

Now object2 is a copy of object1, but deleting properties from object1 will not affect object2.

Hope that makes sense.