我问问

this的引用会改变　　如这段代码：

以下是引用片段： 　　<input type="button" value="Gotcha!" id="MyButton" > 　　<script> 　　var MyObject = function () { 　　this.alertMessage = "Javascript rules"; 　　this.ClickHandler = function() { 　　alert(this.alertMessage ); 　　} 　　}(); 　　document.getElementById(”theText”).onclick =   MyObject.ClickHandler 　　</script>

　　并不如你所愿，答案并不是”JavaScript rules”。在执行MyObject.ClickHandler时，代码中红色这行，this的引用实际上指向的是document.getElementById("theText")的引用。可以这么解决：

以下是引用片段： 　　<input type="button" value="Gotcha!" id="theText" > 　　<script> 　　var MyObject = function () { 　　var self = this; 　　this.alertMessage = “Javascript rules”; 　　this.OnClick = function() { 　　alert(self.value); 　　} 　　}(); 　　document.getElementById(”theText”).onclick =   MyObject.OnClick 　　</script>

　　实质上，这就是JavaScript作用域的问题。

详细说明看这里：http://realazy.org/blog/2007/07/18/scope-in-javascript/

var messageContextMenu = new Ext.menu.Menu({

    id: 'messageContextMenu',

    items: [

        ... menu items ...    ]

});

function onMessageContextItemClick() {}

view.addListener('contextmenu', onMessageContextMenu);

 

function onMessageContextMenu(view, index, node, e) {

    e.stopEvent();

    var coords = e.getXY();

    messageContextMenu.showAt([coords[0], coords[1]]);

} 

动态嵌入 css 代码

var headID = document.getElementsByTagName(”head”)[0];
var cssNode = document.createElement(’link’);
cssNode.type = ‘text/css’;
cssNode.rel = ’stylesheet’;
cssNode.href = ‘FireFox.css’;
cssNode.media = ’screen’;
headID.appendChild(cssNode);

动态嵌入 javascript 代码

var headID = document.getElementsByTagName(”head”)[0];
var newScript = document.createElement(’script’);
newScript.type = ‘text/javascript’;
newScript.src = ‘http://www.somedomain.com/somescript.js’;
headID.appendChild(newScript);

Ajax 就加入 javascript

function ajaxObject(url, callbackFunction) {

var that=this;

this.updating = false;

this.update = function(passData,postMethod) {

if (that.updating==true) { return false; }

that.updating=true;

var AJAX = null;

if (window.XMLHttpRequest) {

AJAX=new XMLHttpRequest();

} else {

AJAX=new ActiveXObject(”Microsoft.XMLHTTP”);

}

if (AJAX==null) {

return false;

} else {

AJAX.onreadystatechange = function() {

if (AJAX.readyState==4) {

that.updating=false;

that.callback(AJAX.responseText,AJAX.status,AJAX.responseXML);

delete AJAX;

}

}

var timestamp = new Date();

if (postMethod==’POST’) {

var uri=urlCall+’?'+timestamp.getTime();

AJAX.open(”POST”, uri, true);

AJAX.setRequestHeader(”Content-type”, “application/x-www-form-urlencoded”);

AJAX.send(passData);

} else {

var uri=urlCall+’?'+passData+’&timestamp=’+(timestamp*1);

AJAX.open(”GET”, uri, true);

AJAX.send(null);

}

return true;

}

}

var urlCall = url;

this.callback = callbackFunction || function () { };

}

function attachScript(responseText, responseStatus) {

// This function is called by the ajaxObject when the server has finished

// sending us the requested script.

if (responseStatus==200) {

eval(responseText);

}

}

// ajaxObject is an object constructor, pass it the server url you want it to call

// and the function name you want it to call when it gets the data back from the server.

// Use the .update() method to actually start the communication with the server.

// The first optional argument for update is the data you want to send to the server.

// ajaxvar.update(’id=1234&greed=good&finish=true’);

// The second optional argument for update is ‘POST’ if you want to send the data

// as a POST instead of the default GET (post can handle larger amounts of data and

// the data doesn’t show up in your server logs).

// ajaxvar.update(’id=1234&greed=good&finish=true’,'POST’);

var getScriptViaAjax=new ajaxObject(’http://mydomain.com/somescript.js’,attachScript);

getScriptViaAjax.update();

var anotherScript = new ajaxObject(’http://mydomain.com/anotherScript.php’,attachScript);

anotherScript.update(’userId=4323′,’POST’);

flickr tag ajax 搜索

<script type=”text/javascript”>

function jsonFlickrFeed(feed){

z=”;

for (x=0; x<feed.items.length; x++) {

tmp=feed.items[x].media.m;

tmp=tmp.replace(/_m\.jpg/g,’_s.jpg’);

z+=’<img src=”‘+tmp+’” mce_src=”‘+tmp+’” alt=”some img” width=”75px” height=”75px” style=”margin: 2px;”>’;

}

document.getElementById(’pics’).style.display=’block’;

document.getElementById(’pics’).innerHTML=z;

}

function searchFlickr() {

var headID = document.getElementsByTagName(”head”)[0];

var newScript = document.createElement(’script’);

tagID = escape(document.getElementById(’tags’).value);

document.getElementById(’tags’).value=”;

newScript.type = ‘text/javascript’;

newScript.src = ‘http://flickr.com/services/feeds/photos_public.gne?tags=’ + tagID + ‘&format=json’;

headID.appendChild(newScript);

document.getElementById(’pics’).style.display=’block’;

document.getElementById(’pics’).innerHTML=”Loading…”;

return false;

}

</script>

<form action = “#” onsubmit=”return searchFlickr();”>

<input type=’text’ size=’40′ id=’tags’>   <input type=’submit’>

</form>

<div style=’border: 1px solid black; width: 100%; display: none;’ id=’pics’></div>

via http://www.hunlock.com/blogs/Howto_Dynamically_Insert_Javascript_And_CSS