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The difference between element and node, Cilldren and childnodes Many friends do not know, this article tries to let you understand the differences between the concepts.
node is a common name for any type of object in the DOM hierarchy, and node has many types, such as element nodes, attribute nodes, text nodes, annotation nodes, etc., which are distinguished by nodetype, and are common:
| node Type | NodeType |
|---|---|
| Elemental Element | 1 |
| Property attr | 2 |
| Textual text | 3 |
| Comment Comments | 8 |
| Document documents | 9 |
More node types reference: https://developer.mozilla.org/en-US/docs/DOM/Node.nodeType?redirectlocale=en-US&redirectslug= NodeType
element inherits the node class, which means that element is one of several types of node , that is, when NodeType is 1 o'clock, node is Elementnode, and element expands node,element ID, class, children, and other attributes.
These are the differences between element and node.
So what do you take with document.getElementById ("xxx") for node or element? Let's test it out:
<!DOCTYPE HTML><HTML><Head> <MetaCharSet= "Utf-8"> <title>Demo</title></Head><Body> <DivID= "Test"> <P>One</P> <P>Both</P> </Div> <Script> varOdiv=document.getElementById ("Test"); Console.log (OdivinstanceofNode); //trueConsole.log (OdivinstanceofElement); //true </Script></Body></HTML>
We can see that document.getElementById ("xxx") takes the element as well as node.
Children is the attribute of element, and ChildNodes is the attribute of node , let's Test it again:
<!DOCTYPE HTML><HTML><Head> <MetaCharSet= "Utf-8"> <title>Demo</title></Head><Body> <DivID= "Test"> <P>One</P> <P>Both</P> </Div> <Script> varOdiv=document.getElementById ("Test"); Console.log (odiv.children[0] instanceofNode); //trueConsole.log (odiv.children[0] instanceofElement); //trueConsole.log (odiv.childnodes[0] instanceofNode); //trueConsole.log (odiv.childnodes[0] instanceofElement); //falseConsole.log (typeofodiv.childnodes[0].children); //undefinedConsole.log (typeofodiv.childnodes[0].childnodes); //Object </Script></Body></HTML>
As we can see from the above code, element children[0] is still element, which is an instance of node and element, node's childndoes[0] is node, just an instance of node, not an instance of element.
At the same time,node's Children property is undefined.
When I take a child element with children[0] Instead, you can use the corresponding method Getboundingclientrect () to get the position of the element
It is sometimes obtained when using childnodes to get [object htmldlistelement], but occasionally it gets [object Text].
Some people say that it is a browser problem, but I use the Firefox test, and then I found that [object Text] is because I changed the line childnodes gave me a space when the first node, remove the line is OK
The difference between element and node in JavaScript, the difference between children and childnodes
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