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Learn the next "JS DOM programming Art", to do a study summary:
1. Enclose single quotation marks in a string:
Suggestions:
Enclose a single quotation mark in a string, enclose the string in double quotation marks
1 var s1= "It ' s My Doy";
Enclose double quotation marks in a string, enclose the string in single quotation marks
1 var s2= ' He said "hi!" ';
Other uses \ to escape
2.== and = = =
= = = Strict comparison. Not only compare values, but also compare types
= =: Non-strict comparison, conversion type consistent comparison
Three types of objects in 3.JS languages
3.1 Built- in Objects : JavaScript-supplied objects Math Array
3.2 Host Object : Browser object. such as Document,window
3.3 User Custom objects:..
4. Get the objects in the document
1 document.getElementById ("P1");
1 document.getelementbytagname ("input");
1 document.getelementbyclassname ("classname1 classname2"); // Note: The name order is not important at this time, can be disorderly
5. Get an object property
eg
var html=document.getelementsbytagname ("html");//html array
Html[0].getattribute ("title");//The result is null at this time, which means no value
html[0].title;//The result is ""; there may be a compatibility issue with the old version of the Web document processing mode
6.event event returns false to cause the default behavior to not be triggered
eg
1 < href= "www.baidu.com" onclick= "return false">onclick </ a >//Click the link at this time, jump to the Baidu page of the event will not trigger
7. Get the child nodes of a node
var child=document.getelementsbytagname ("body") [0].childnodes;
Child.length;
Child[0].nodetype; // returns a number with a result of 1 2 3. Where: 1-element node, 2-Attribute node, 3-text node
8. Get the value of a text node
Element.nodevalue;
eg
1 <Body>2 ********test nodetype,nodevalue*******3 <P>Hello Jermy</P>4 <Scripttype= "Text/javascript">5 functiontag (tagname) {6 returndocument.getElementsByTagName (tagname) [0];7 }8 varP1=Tag ("P");9 varT1=P1.firstchild;//equivalent to p1.childnodes[0]Ten document.write ("p1.nodetype="+P1.nodetype+";p 1.nodevalue="+P1.nodevalue+"<br/>"); One document.write ("t1.nodetype="+T1.nodetype+"; t1.nodevalue="+t1.nodevalue); A </Script> - </Body>
9. Pseudo-Protocol (note: This method is not recommended)
<a href= "Javascript:prop ()" ></a>//here click a link, in support of the pseudo-protocol browser run directly, do not support the pseudo-protocol browser will error. Pseudo-protocol support but the user-disabled JS browser will do nothing.
Website design Focus: smooth degradation
One. Line wrap String
1 document.getElementById ("Demo"). InnerHTML = "Hello \ 2 dolly!";
12. Self-booting:
1 (function () { 2 document.getElementById ("Demo"). InnerHTML = "hello! I called myself "; 3 } ());
Or:
1 (function () { 2 document.getElementById ("Demo"). InnerHTML = "hello! I called myself "; 3 }) ();
13. Examples of closures
1 <!DOCTYPE HTML>2 <HTML>3 <Body>4 5 <P>Counting with a local variable.</P>6 7 <Buttontype= "button"onclick= "myFunction ()">count!</Button>8 9 <PID= "Demo">0</P>Ten One <Script> A varAdd= (function () { - varcounter= 0; - return function () {returncounter+= 1;} the })(); - - functionmyFunction () { - document.getElementById ("Demo"). InnerHTML=Add (); + } - </Script> + A </Body> at </HTML>
Closure results See picture
JS Learning 12-"JS DOM programming Art" notes
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