Question

I have a variable d that I use like this:

$(function() {       for(i = 1; i <= 31; i++) {         var d = '#days' + i;             if ($(d).attr('id').substr(4,2) == 11) {             $(d).addClass('date_has_event');             //console.log('diez');         } else {             console.log('otro');         }     } } 

However I get the following error in firebug:

  $(d).attr('id') is undefined index.html    (L23)   (?)()() jquery.min.js (L27)   onreadystatechange()() jquery.min.js (L27)   onreadystatechange()() jquery.min.js (L21)   nodeName()([function(), function()], function(), undefined) onreadystatechange()()  

I really don’t understand why. Does anyone know?

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Edit

I’m sorry for the poor explanation I had to run, here’s what’s going on a little bit more detailed. I am generating a calendar using javascript. each td has a different id (hence the #days + i) and I am running it from 1 to 31 so I can cover the longer months. However I am getting the error I mentioned above. I am also using the jQuery library to enable me to select more easily (i.e. instead of getElementById just #days)

Answer 1

Why not just check if i == 11, then do your processing on it? It would still only fire on $('#days11'). Edit: If you need to make sure the element exists as well, just slap that into the conditional.

$(function(){        for(i = 1; i <= 31; i++){         var d = '#days' + i;      //       if($(d) && i == 11){                      if(i == 11){                $(d).addClass('date_has_event');                //console.log('diez');          }else{                console.log('otro');          }     } }