What are you trying to do? Have you read an html file into PHP so its a string and you wish to read it out or are you try to access once the page has loaded, in which case this sounds like a Javascript question to me.
You can read the with parameter in Javascript using document.getElementById('id').width where id is the id of the table. If the table does not have an id, which most won't, you could use a loop such as
var tagList = document.getElementsByTagName('table');
for( a=0; a < tagList.length; a++ ){
// do something ...
}
but you'll need to perform checks to make sure you pick up the correct table. An example would be to use the innerHTML.match method which is supported by IE and mozilla.
So if the table contained the text "Posts:" somewhere you could use this within the loop
if( tagList[a].innerHTML.match("Posts: ") 0 {
// Do something
}
