How do I print JavaScript errors to the screen?

[atrum]

Hello all,

 

I have little experience with javascript, but I am trying to change that.

 

Today it dawned on me that learning how to script in javascript would be alot easier if I could see all the errors my code is putting out.

 

For example in PHP, if I wanted to see any errors that my code may produce, I would simply enter.

 

ini_set('display_errors','On');

 

How can I do that for javascript?

 

Thank you in advance for your help.

[RichardRotterdam]

try installing the firebug plugin for firefox

[darkfreaks]

if firebug on firefox doesn't solve your problems, http://www.jslint.com will debug your code error by error. if it is plain javascript and not a javascript library.

[atrum]

Do you think something like this would work?

 

onerror=handleErr
var txt=""

function handleErr(msg,url,l)
{
txt="There was an error on this page.\n\n"
txt+="Error: " + msg + "\n"
txt+="URL: " + url + "\n"
txt+="Line: " + l + "\n\n"
txt+="Click OK to continue.\n\n"
alert(txt)
return true
} 

 

I dont really like that it comes up in a popup box. Is there a way to make this just write the error to the screen?

[darkfreaks]

onerror=handleErr;
var txt="";

function handleErr(msg,url,l)
{
txt="There was an error on this page.\n\n";
txt+="Error: " + msg + "\n";
txt+="URL: " + url + "\n";
txt+="Line: " + l + "\n\n";
txt+="Click OK to continue.\n\n";
alert(txt);
return true;
} 

 

should use semicolons after your variables there

 

also i hope you defined handleERR before you output it might have problems if you do not 

 

also should never use document.write or alert to output stuff. as its too global.

call errors like this:

var div = document.createElement('div');
div.className = 'foo';
div.appendChild(document.createTextNode('this is an error'));
document.body.appendChild(div);