What is the difference between using the delete operator on the array element as opposed to using the Array.splice method?
For example:
myArray = ['a', 'b', 'c', 'd'];
delete myArray[1];
// or
myArray.splice (1, 1);
Why even have the splice method if I can delete array elements like I can with objects?
Because delete only removes the object from the element in the array, the length of the array won't change. Splice removes the object and shortens the array.
The following code will display "a", "b", "undefined", "d"
myArray = ['a', 'b', 'c', 'd']; delete myArray[2];
for (var count = 0; count < myArray.length; count++) {
alert(myArray[count]);
}
Whereas this will display "a", "b", "d"
myArray = ['a', 'b', 'c', 'd']; myArray.splice(2,1);
for (var count = 0; count < myArray.length; count++) {
alert(myArray[count]);
}
From Core JavaScript 1.5 Reference > Operators > Special Operators > delete Operator :
When you delete an array element, the array length is not affected. For example, if you delete a[3], a[4] is still a[4] and a[3] is undefined. This holds even if you delete the last element of the array (delete a[a.length-1]).
It's probably also worth mentioning that splice only works on arrays. (Object properties can't be relied on to follow a consistent order.)
To remove the key-value pair from an object, delete is actually what you want:
delete myObj.propName; // , or:
delete myObj["propName"]; // Equivalent.