This function returns a new instance of class DOMElement. The tag name of the element is the value of the name parameter. Optionally, a value for the new element may also be passed in. 本节点不会出现在文档中，除非是用例如 DOMNode->appendChild() 来插入的。
The return value is FALSE if an error occurred.
See also DOMDocument->createElementNS(), DOMNode->appendChild(), DOMDocument->createTextNode(), DOMDocument->createComment(), DOMDocument->createAttribute(), DOMDocument->createProcessingInstruction().