Wierd behavior of alert box function

[rycerz1411]

This is wierd behavior in IE 6 (works in FireFox)
This overrides alert function correctly 'function alert (s,t,icon)' but this
'window.alert=function(s,t,icon)' does not, the strangest part is that
' window.prompt=function(string,defaultValue,fun,funArguments,scope)' does behave correctly and overrides the prompt function.

The thing that I don't see is why alert function cant be overwritten this same way even that it resides in window scope.

[toicontien]

There might be a small JavaScript error maybe? Can we see the full function definitions for both window.prompt and window.alert?

[rycerz1411]

Here is complete code :

var alert_w=alert;
var dialog;
var buttons=[]
var confirmationResult=false;
var confirmEven=new YAHOO.util.CustomEvent("Confirmation Event");
AlertOveride = function(){
    // return a public interface
    return {
		//Initalize the component
        init : function(){
			
        },
        showDialog : function(properties){
            if(!dialog){
                dialog = new YAHOO.ext.BasicDialog("alert-dlg", {
                        modal:true,
                        autoTabs:false,
					    autoScroll:true,
			            resizable:false,
                        width:width,
                        height:height,
                        shadow:true,
			            draggable:true
	               });

					buttons["cancel"]=dialog.addButton('Cancel', function(){dialog.hide();confirmEven.fire(false);} , dialog)
					buttons["ok"]=dialog.addButton('Ok', function(){dialog.hide();confirmEven.fire(true);} , dialog);
					buttons["close"]=dialog.addButton('Close',  function(){dialog.hide();}  , dialog);

				}// lazy initialize the dialog and only create it once

				if(properties.confirm || properties.prompt){
					buttons["cancel"].setVisible(true);
					buttons["ok"].setVisible(true);
					buttons["close"].setVisible(false);
				}else{
	               	buttons["cancel"].setVisible(false);
					buttons["ok"].setVisible(false);
					buttons["close"].setVisible(true);
				}

				var width = 130 + properties.width
				var height =  90 + properties.height
				if(width<220)width=220;
				if(height<90)height=90;
				dialog.resizeTo(width, height);
				dialog.show();
        }
    };
}
	
var isConfirm=false;
var isPrompt=false;

//Overide window.confirm  box
 window.confirm=function(string,fun,funArguments,scope){
	 this.isConfirm=true;
	 var response=false;
	 var ccInterval=0;
	 if(funArguments==null)funArguments=[];
		alert(string, 'Confirmation', 'question');
		confirmEven.subscribe(function(e,arg){
			if(scope==null)scope=this;
				funArguments[funArguments.length]=arg;
				fun.apply(scope,funArguments)
				confirmEven.unsubscribeAll();
		});
		this.isConfirm=false;
 }

 window.prompt=function(string,defaultValue,fun,funArguments,scope){
	 this.isPrompt=true;
	 var response=false;
	 document.getElementById('prompt-input-text').value=defaultValue;
	 if(funArguments==null)funArguments=[];
		alert(string, 'Prompt', 'question', true);
		confirmEven.subscribe(function(e,arg){
			if(scope==null)scope=this;
			//This simulates the behavior of standard input returning 'null' if the cancel button was pressed
				var promptValue=document.getElementById('prompt-input-text').value;
				if(arg[0]==true){//OK Button Pressed
					funArguments[funArguments.length]=promptValue;
				}else{//Cancel Button Pressed
					funArguments[funArguments.length]=null;
				}
				fun.apply(scope,funArguments)
				confirmEven.unsubscribeAll();
		});
		this.isPrompt=false;
 }

 //overiding default alert box
 /**
 * This is wierd behavior in IE 6   this overides  alert function correctly  'function alert (s,t,icon)'  but this 
 * 'window.alert=function(s,t,icon)'  does not.
 */
function alert (s,t,icon){
 document.getElementById('prompt-input').style.display='none';
 if(!t || t=='undefined'){
	t="Alert";
 }
 var eIcon=getEl('alert-icon');
	eIcon.dom.className='msg-alert-icon';
	if(icon){
		switch(icon){
			case 'alert':eIcon.dom.className='msg-alert-icon'; break;
			case 'question':eIcon.dom.className='msg-question-icon'; break;
			case 'info':eIcon.dom.className='msg-info-icon'; break;
			case 'prompt':eIcon.dom.className='msg-prompt-icon'; break;
			default:eIcon.dom.className='msg-alert-icon'; break;
		}
	}
	 s=new String(s).replace(new RegExp("\\n", "g"),"<br />");//Preserve \n

	 var bodyData=document.getElementsByTagName('BODY')[0];
	 //Check for previous instance of the alert-contentDivSize
	 var d_nested = document.getElementById("alert-contentDivSize");
	 if(d_nested!=null){
		 bodyData.removeChild(d_nested);
	  }

	 var contentDiv=document.createElement('div');

	 contentDiv.style.position='absolute';
	 contentDiv.style.display='';
	 contentDiv.id='alert-contentDivSize';
	 bodyData.appendChild(contentDiv);

	 contentDiv.innerHTML=s;
	 var region=getEl('alert-contentDivSize').getRegion();
		 contentDiv.style.display='none';
	 var height=region.bottom-region.top;
	 var width=region.right-region.left;

	 if(this.isConfirm){
		height+=10;
	 }

	 if(this.isPrompt){
	 document.getElementById('prompt-input').style.display='';
	 //Keeping proportions
		height+=25;
		width+=25;
	 }

	var at=getEl('alert-title');
	var am=getEl('alert-message');
	at.dom.innerHTML=t;
	am.dom.innerHTML=s;
	var alertdialog=new AlertOveride();
	alertdialog.init();
	return alertdialog.showDialog({height:height,width:width,confirm:this.isConfirm,prompt:this.isPrompt});

 }

This is puzzling.

[smeezekitty]

what are u trying to make the alet message do?

[rycerz1411]

Here is the result.(See attached file).

Really what I am concerned with here is the behavior of overriding the alert box
Thanks.

[toicontien]

This code worked for me:

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
  "http://www.w3.org/TR/html4/strict.dtd">

<html>
<head>
<title>Overwrite alert() function</title>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
<script type="text/javascript">
<!-- begin hiding
window.alert = function() {
  document.getElementsByTagName('body')[0].appendChild(document.createTextNode('AAAH! '));
};

window.onload = function() {
  alert();
};
// end hiding -->
</script>
</head>
<body>
</body>
</html>

One small suggestion -- and I don't know how much it will affect things -- but any time you do foo = function() {}, you should to end it with a semi colon, as you are actually assigning a value to something. similar to var foo = "bar";.

So it should look like:

window.alert = function() {
  // your code here
}; // <<--- semi colon

Since JavaScript recognizes newline characters as the end of a programming line, it shouldn't make a difference. Something else must be going on. What part of the HTML document is this JavaScript being included in? Was there a JavaScript error that perhaps was fixed when you changed the function definition to "function alert()"?

[rycerz1411]

thanks for the suggestion toicontien,

Your code did work on IE and FF as expected.

function alert (s,t,icon){
}

window.alert=function(s,t,icon){
};

This two function declarations should be this same, all I did was change how the function was declared to get it working in IE, so I really don't think that there were any bugs introduced of fixed.

Thanks for you input.

[chandiran84]

hai,
i want override a alert box, please send me a details code for this


by
chandiran.r

[toicontien]

window._alert = alert;

window.alert = function (str) {
  // Do stuff
};

alert("Over written alert");

_alert("Original alert");