Javascript replace()

[klads]

A small part of my web site allows a user to enter a warning message that will appear on the login html page.

The message is captured in a textarea input field. Once the form is submitted a Java process replaces any occurences of '\r\n' with </br> and saves the text to a .txt file on the web server.

The login html page then uses a bit of Ajax to retrieve the .txt file and displays the content it if not empty.

This all works perfecty in both IE7 and Firefox 18.0.2.

To allow the user to amend the message I wish to read it from the web server and display it in the same textarea input field. Prior to display I am attempting to replace the </br> with '\r\n'.

This works in Firefox and but IE7 seems to replace the </br> with space. My Javascript code is as follows. Any help would be greatly appreciated.

	var http = createRequestObject();

	function createRequestObject() {
		var objAjax;
		var browser = navigator.appName;
		if (browser == "Microsoft Internet Explorer") {
			objAjax = new ActiveXObject("Microsoft.XMLHTTP");
		} else {
			objAjax = new XMLHttpRequest();
		}
		return objAjax;
	}

	function getWarningMessage(){
		var rightNow = new Date();
		http.open('get','/warningmessage/warningmessage.txt?' + rightNow.getTime());
		http.onreadystatechange = updateNewContent;
		http.send(null);
		return false;
	}

	function updateNewContent(){
		var warningMessage;
		var warningMessageReplace;
		if (http.readyState == 4 && http.responseText.length > 0){
			warningMessage = http.responseText;
			while (warningMessage.search('</br>') > 0) {
				warningMessageReplace = warningMessage.replace('</br>','\r\n');
				warningMessage = warningMessageReplace;
			}
			document.getElementById('warningMessage').innerHTML = warningMessage;
		}
	}

[Philip M]

You need to make the regex case-insensitive for IE. I am surprised that your code works in any browser as / must be escaped with \.

warningMessageReplace = warningMessage.replace(/<\/br>/gi,'\r\n');

If you are 20 and you are not a socialist, then you have no heart. If you are 40 and you are still a socialist, then you have no brain.

[felgall]

What is the purpose of:

if (browser == "Microsoft Internet Explorer") {
			objAjax = new ActiveXObject("Microsoft.XMLHTTP");
		} else {
			objAjax = new XMLHttpRequest();
		}

All browsers now recognise XMLHttpRequest and the navigator.appName can contain "Microsoft Internet Explorer" in Firefox, Opera, Chrome or Safari masquerading as Internet Explorer and Intertnet Explorer can be set to identify itself as any other browser. Even if you do need to include the activeX call to support the dead IE6 browser then there are more accurate ways to difect that call specifically to IE4 through IE6 that don't interfere with other browsers being able to use the call that they recognise.

[Old Pedant]

As Felgall said.

One better way (and there are others, but this works for me) is:

function createRequestObject() {
    return   ( XMLHttpRequest != null )
           ? new XMLHttpRequest( ) 
           : new ActiveXObject("Microsoft.XMLHTTP");
}

Another seemingly popular way:

function createRequestObject() 
{
    try {
        return  new XMLHttpRequest();
    } catch ( ignored ) { }
    try {
        return new ActiveXObject("Microsoft.XMLHTTP");
   } catch ( oops ) {
        return null;
   }
}

[felgall]

Originally Posted by Old Pedant

As Felgall said.

One better way (and there are others, but this works for me) is:

function createRequestObject() {
    return   ( XMLHttpRequest != null )
           ? new XMLHttpRequest( ) 
           : new ActiveXObject("Microsoft.XMLHTTP");
}

Another seemingly popular way:

function createRequestObject() 
{
    try {
        return  new XMLHttpRequest();
    } catch ( ignored ) { }
    try {
        return new ActiveXObject("Microsoft.XMLHTTP");
   } catch ( oops ) {
        return null;
   }
}

Of course with IE6 being dead you can even drop the activeX reference completely and just use new XMLHttpRequest() since all the browsers people current use support it.

[klads]

Although IE6 may be "dead" to the wider browsing community...it is still alive and well in my company and, as a such, still needs supported. Hopefully not for long but that's the position I'm in.