Using the += operator, you can insert an XML element at the end of a list of sibling elements. (Note that this operator is equivalent to using the appendChild function described in Functions for Manipulating XML.)
This can be useful when you want to insert a new element into an existing list, as in the following example.
/* Declare an XML variable with a literal XML value. */ var xmlEmployees = <employees> <employee> <firstname>John</firstname> <lastname>Walton</lastname> <age>25</age> </employee> <employee> <firstname>Gladys</firstname> <lastname>Cravits</lastname> <age>53</age> </employee> </employees>; /* Insert a new node with information about Rob Petrie at the end of the list */ xmlEmployees..employee[1] += <employee id = "333333333"> <firstname>Rob</firstname> <lastname>Petrie</lastname> <age>34</age> </employee>;
This operator can't be used in cases where the left operand is an XMLList, as in the following example. This example attempts to insert the new <employee> element at the end of the list by omitting a specific reference to a particular element (as in the preceding example). To insert an element as the last in a list, use the appendChild function.
/* This causes a run-time error. */ xmlEmployees.employee += <employee> <firstname>Sue</firstname> <lastname>Day</lastname> <age>32</age> </employee>;