Tuesday, April 29, 2008

Inspecting object in javascript

An interesting problem is to inspect unknown objects in javascript. Found a good example of how to do it here. Just to rehash in case the site move:

function inspect(obj, maxLevels, level)
{
var str = '', type, msg;

// Start Input Validations
// Don't touch, we start iterating at level zero
if(level == null) level = 0;

// At least you want to show the first level
if(maxLevels == null) maxLevels = 1;
if(maxLevels < 1)
return '<font color="red">Error: Levels number must be > 0</font>';

// We start with a non null object
if(obj == null)
return '<font color="red">Error: Object <b>NULL</b></font>';
// End Input Validations

// Each Iteration must be indented
str += '<ul>';

// Start iterations for all objects in obj
for(property in obj)
{
try
{
// Show "property" and "type property"
type = typeof(obj[property]);
str += '<li>(' + type + ') ' + property +
( (obj[property]==null)?(': <b>null</b>'):('')) + '</li>';

// We keep iterating if this property is an Object, non null
// and we are inside the required number of levels
if((type == 'object') && (obj[property] != null) && (level+1 < maxLevels))
str += inspect(obj[property], maxLevels, level+1);
}
catch(err)
{
// Is there some properties in obj we can't access? Print it red.
if(typeof(err) == 'string') msg = err;
else if(err.message) msg = err.message;
else if(err.description) msg = err.description;
else msg = 'Unknown';

str += '<li><font color="red">(Error) ' + property + ': ' + msg +'</font></li>';
}
}

// Close indent
str += '</ul>';

return str;
}

1 comment:

Anonymous said...

Thanks for the posting. This example worked when all of the other ones I tried failed.

Haiya ala Solah