Get rid of Notice: Undefined index: php error message
This message "Notice: Undefined index:" shows up in php pages when an element does not exist in an array, e.g.
if($arr[’$elementName’])…
The cure is simple: put isset() around it. e.g.:
if(isset($arr[’$elementName’]))
If lines of text inside the pre tag are too long it may mess up the page layout in IE.
Use the following style from Tero Karvinen:
white-space: pre-wrap; /* css-3 */
white-space: -moz-pre-wrap; /* Mozilla, since 1999 */
white-space: -pre-wrap; /* Opera 4-6 */
white-space: -o-pre-wrap; /* Opera 7 */
word-wrap: break-word; /* Internet Explorer 5.5+ */
Let’s say you want to bring down a list of names from the server and display them without reloading the page.
I’ll show you a simple way to do it using the Ajax technology.
1. Create a form:
<form name="frm" action="#" autocomplete=off onSubmit="getIt();return false;">
<fieldset>
<label for "id">Enter name:</label>
<input size="20" type="text" id=’id’ name="name" value='’><BR>
<input type="submit" name="doit" value="submit">
</fieldset>
</form>
The submit even will call a JavaScript function getIt(). We’ll get to it later.
2. Create a div
<div id=result> </div>
3. Get a reference to XMLHttpRequest object.
function getHTTPObject() {
if (typeof XMLHttpRequest != ‘undefined’)
{ return new XMLHttpRequest(); }
try { return new ActiveXObject("Msxml2.XMLHTTP"); }
catch (e)
{ try { return new ActiveXObject("Microsoft.XMLHTTP"); }
catch (e) {} }
return false; }
var xmlhttp = getHTTPObject();
4. Create a getIt() function:
function getIt( ) {
if( xmlhttp) {
var url =’servlet/myClass’;
var target = document.getElementById("id");
url += "?id=" + encodeURIComponent(target.value);
xmlhttp.open(’GET’, url, true);
xmlhttp.send(null);
var divResult =document.getElementById(’result’);
xmlhttp.onreadystatechange = function (){
if (xmlhttp.readyState == 4) {
if (xmlhttp.status == 200) {
divResult.innerHTML = xmlhttp.responseText;
}
}
}
}
}
Here’s a simple way to generate an hourglass on demand, regardless of what the mouse is over.
Create a document-element class:
html.waitCursor * { cursor: wait; }
When the <html> tag has a class of "waitCursor", the mouse would become an hourglass over the entire page and all elements, including any margin outside the BODY area. Create a pair of simple functions that can be called in global scope:
function beginWait { document.documentElement.className = ‘waitCursor’; }
function endWait { document.documentElement.className = ‘’; }
From John Black on http://swik.net/Ajax/Ajax+Mistakes
If you want to use DOM to create a table row with a cell that has a colSpan attribute you are in for a surprise. Internet Explorer will produce an error if you try to set a colSpan attribute on a cell element.
Here is the solution:
var tr = document.createElement(’tr’);
if(!document.all) {
// non-IE browsers
var td = tr.insertCell(0);
td.colSpan = 4;
td.align = "center";
}
else {
//IE code
var td = document.createElement(’<td colspan="4" align="center"></td>’);
}
td.innerHTML = "HELLO";
tr.appendChild(td);
