JavaScript determines object type and node type, node name, and node value

One, JavaScript to determine the object type 1, you can use the TypeOf function to determine the object type

1 function CheckObject1 () {2     var str= "str"; 3     Console.log (typeof(str))// Output "string"; 4     Console.log (typeof(str) = = "string")// output true; 5 }?

2. Use the object's constructor property (constructor) to determine the object's type:

1 function CheckObject2 () {2  var str = "str"; 3  Console.log (str.construtor== "string")// output 4 }

3, the difference between the two

The TypeOf function can only be judged by the type of object:

(1) Boolean

(2) function

(3) Number

(4) Object

(5) string

(6) undefined

The use of the Construtor property can be used to determine a complex type. Like what

1 //a complex type of object that determines its type2 functionUser (name, age) {3      This. name=name;4      This. age=Age ;5 }6 functioncheckcomplexobj () {7     varS= ' A string ';8     varArr=[];9     varobj=NewObject ();Ten     varUsr=NewUser ();//Custom Objects OneConsole.log (' s.constructor==string: ' + (s.constructor==string));//Output True AConsole.log (' Arr.constructor==array: ' + (Arr.constructor==array));//Output True -Console.log (' Obj.constructor==object: ' + (obj.constructor==object));//Output True -Console.log (' Usr.constructor.name==user: ' + (Usr.constructor.name==user));//Output True the}

Second, use JavaScript to determine the node type, node name and node value 1, node type classification

node Type	Description	value
ELEMENT node	Each HTML tag is an element node, such as <div>, <p>, <ul>, and so on	1
Attribute node	Attributes of ELEMENT nodes (HTML tags), such as ID, class, name, and so on.	2
Text node	The text content in the element node or attribute node.	3
Comment Node	Represents a document comment in the form <!--comment text---.	8
Document node	Represents the entire document (the root node of the DOM tree, which is document)	9

2. Use JavaScript to determine node type, node name and node value

1<!--use JavaScript to determine the node type--2<div id= "Onediv" > a text </div><!--comment text--3<script type= "Text/javascript" >4     vardiv = document.getElementById ("Onediv");5Console.log (Div.nodetype);//output 1, element node6     varDivtext =Div.firstchild;7Console.log (Divtext.nodetype)//output 3, text node8     varDivattr = Div.getattributenode ("id");9Console.log (Divattr.nodetype)//output 2, attribute nodeTen     varComment =div.nextsibling; OneConsole.log (Comment.nodetype)//output 8, note node A</script>

1<!--using JavaScript to determine node names--2<div id= "Onediv" > a text </div><!--comment text--3<script type= "Text/javascript" >4     vardiv = document.getElementById ("Onediv");5Console.log (Div.nodename);//output div, element node is tag uppercase6     varDivtext =Div.firstchild;7Console.log (Divtext.nodename)//output #text, text nodes are always #text when using nodename8     varDivattr = Div.getattributenode ("id");9Console.log (Divattr.nodename)//output ID, attribute node is property nameTen     varComment =div.nextsibling; OneConsole.log (Comment.nodename)//output #comment, note nodes are always #comment when using nodename A</script>

1<!--use JavaScript to determine node values--2<div id= "Onediv" > a text </div><!--comment text--3<script type= "Text/javascript" >4     vardiv = document.getElementById ("Onediv");5Console.log (Div.nodevalue);//output NULL, element node not supported for NodeValue6     varDivtext =Div.firstchild;7Console.log (Divtext.nodevalue)//output a text, text node output text value8     varDivattr = Div.getattributenode ("id");9Console.log (Divattr.nodevalue)//output Onediv, attribute node output property valueTen     varComment =div.nextsibling; OneConsole.log (Comment.nodevalue)//output comment text, comment node output comment content A</script>

JavaScript determines object type and node type, node name, and node value