var arr = ['a','b','c','d','e']; delete arr; //arr is now ['a', 'b', undefined, 'd', 'e']
As you can see from the above code, the element is removed but this leaves a hole in the array because the element was replaced with undefined.
Therefore, the correct way to remove an element an array from an element is by using the splice method.
var arr = ['a','b','c','d','e']; arr.splice(2, 1); //arr is now ['a', 'b', 'd', 'e']
The first argument is an index (ordinal) in the array from where to start deleting and the second element is the number of elements to delete. Thus, with 2 and 1 as parameters, we are starting at index 2 and removing 1 element. (Additional parameters get inserted into the array).
One thing to note is that with splice, the property with the value 'd' has it's key changed from 4 to 3 and because every property after the deleted property will be removed and reinserted with a new key, this might take a while for large arrays.