1. document.createElement (); you need to pass in a tag name as a parameter. You will create a corresponding node according to the tag name and return the node. document.createTextNode (); you need to pass in a text content as the parameter appendChild ()

	Usage: parent element.appendChild( child node ).

A child of a node can be inserted before the new node

	Usage: Parent node. insertBefore( new node, old node );

Replacechild(); replace child node

	Usage: parent.replaceChild( new node, old node );

Removechild(); can delete a child node

	Usage: parent.removeChild(child node).

InnerHTML can also be used to add dom. Generally, the two methods are combined.

	e.g. city.innerHTML += " <li>GuangZhou</li> ";

Confirm (“); a prompt box with confirm and Cancel buttons will pop up. If the user clicks confirm, it will return true; otherwise, it will return false </ OL>