$(document).ready(function() {
var fileTypes = {
  // extension: 'image file'
  doc: 'doc.gif',
  xls: 'xls.gif',
  pdf: 'http://www.rencontres-cinema-nature.eu/wp-content/themes/rcn/images/icone_pdf.gif'
};

// then, loop over the object
// using jQuery's $.each()
$.each(fileTypes, function(extension,image) {
  $('a[href$="' + extension + '"]').
    css({
      paddingLeft: '20px',
      paddingTop: '2px',
      paddingRight: '2px',
      background: 'transparent url("' + image + '") no-repeat center left'
    });
});

});