using href attribute as parameter in grep

Im trying to use the href attribute of a link to filter a json array with grep.

The grep works fine when the href value is hard coded into the grep parameter, (ie, el.category_name.toLowerCase() === "y"), but it doesnt work when I try to add the href dynamically as a variable from the button's href arrtibute.

I think it might be a question of scope... but Im not sure how to set up the variable.

Any help would be very much appreciated.

This is what I've been trying --

$('#categ开发者_开发知识库ory_name').click(function()
  {
    var href = $(this).attr('href');

    $.getJSON('data/all.json',
      function(data)
      { 
        location = $.grep(data, function(el, i)
         { 
          return 'el.' + href + '.toLowerCase() === "y"'
         });

      //returned grep-ed objects mapped to html//

     });
   });

Try this

$('#category_name').click(function()
  {
    var href = $(this).attr('href');

    $.getJSON('data/all.json',
      function(data)
      { 
        location = $.grep(data, function(el, i)
         { 
          return el[href].toLowerCase() === "y"'
         });

      //returned grep-ed objects mapped to html//

     });
   });