Improvements to the picture library of JavaScript DOM programming art notes

Principles to be followed for DOM operations

1. Smooth degradation

2. Separating JavaScript

3. Backwards compatibility

4. Performance Considerations

Improved display image method

functionShowpic (whichpic) {if(!document.getelementbyid ("placeholder"))return false; varSource=whichpic.getattribute ("href"); varPlaceholder=document.getelementbyid ("placeholder"); if(placeholder.nodename!= "IMG")return false; Placeholder.setattribute ("SRC", source); if(document.getElementById ("description")){    varText=whichpic.getattribute ("title")? Whichpic.getattribute ("title"): ""; varDescription=document.getelementbyid ("description"); if(description.firstchild.nodetype==3) {Discription.firstChild.nodeValue=text; }    }    return true;}

Newly added separation of HTML and JavaScript methods

functionPreparegallery () {if(!document.getelementbyid)return false; if(!document.getelementbytagname)return false; if(!document.getelementbyid ("Imagegallery"))return false; varGallery=document.getelementbyid ("Imagegallery"); varLink=gallery.getelementbytagname ("a");  for(vari=0; I<link.length; i++) {Link[i].onclick=function(){            returnShowpic ( This) ?false:true; }    }}

Ways to add events

function Addloadevent (func) {    var oldonload=window.onload;     if (typeof window.onload!= ' function ') {        window.onload=func;    } Else {        window.onload-function() {            oldonload ();            Func ();        }    } }

Improvements to the picture library of JavaScript DOM programming art notes