detect brokenlinks

brokenlinks.js

// inspired by https://stackoverflow.com/questions/1591401/javascript-jquery-check-broken-links

function urlExists(element, callback) {
  var xhr = new XMLHttpRequest();
  xhr.onreadystatechange = function() {
    if (xhr.readyState === 4) {
      callback(xhr.status < 400);
    }
  };
  xhr.open('HEAD', element.attr("href"));
  xhr.send();
}

$(function() {
    $( "a" ).each(function( index ) {
        var element = $(this);
        urlExists(element, function(exists) {
            console.log('"%s" exists?', element.attr("href"), exists);
            if (!exists) {
                element.addClass("brokenlink");
            }
        });
    });
});