Getting screen reader to read new content added with JavaScript

33
votes

When a web page is loaded, screen readers (like the one that comes with OS X, or JAWS on Windows) will read the content of the whole page. But say your page is dynamic, and as users performing an action, new content gets added to the page. For the sake of simplicity, say you display a message somewhere in a <span>. How can you get the screen reader to read that new message?

2
javascriptaccessibilityscreen-readers
Screen readers do read form fields and links when they get the focus. So one possibility is to put an anchor around the text and set the focus to that anchor. With CSS you can get the link not to show as a link for users looking at the page. But this method isn't very satisfactory as screen reader users will be falsely led to believe that this is a link. – avernet
Add tabindex to any element and it will become readable, I believe (tabindex=-1 makes it scriptable but not tabbable). I often programmatically send focus to new content after a link is clicked (like a tab switcher or accordion) -- but it doesn't have to be a link to be focusable. Read up on tabindex. – Marcy Sutton

2 Answers

36
votes

The WAI-ARIA specification defines several ways by which screen readers can "watch" a DOM element. The best supported method is the aria-live attribute. It has modes off, polite,assertive and rude. The higher the level of assertiveness, the more likely it is to interrupt what is currently being spoken by the screen reader.

The following has been tested with NVDA under Firefox 3 and Firefox 4.0b9:

<!DOCTYPE html>
<html>
<head>
  <script src="js/jquery-1.4.2.min.js"></script>
</head>
<body>
  <button onclick="$('#statusbar').html(new Date().toString())">Update</button>
  <div id="statusbar" aria-live="assertive"></div>
</body>

The same thing can be accomplished with WAI-ARIA roles role="status" and role="alert". I have had reports of incompatibility, but have not been able to reproduce them.

<div id="statusbar" role="status">...</div>
1
votes

Here is an adapted real world example -- this up-level markup has already been converted from an unordered list with links into a select menu via JS. The real code is a lot more complex and obviously could not be included in its entirety, so remember this will have to be rethought for production use. For the select menu to be made keyboard accessible, we registered the keypress & onchange events and fired the AJAX call when users tabbed off of the list (beware of browser differences in timing of the onchange event). This was a serious PITA to make accessible, but it IS possible.

  //  HTML

  <!-- select element with content URL -->
  <label for="select_element">State</label>
  <select id="select_element">
     <option value="#URL_TO_CONTENT_PAGE#" rel="alabama">Alabama</option>
  </select>
  <p id="loading_element">Content Loading</p>

  <!-- AJAX content loads into this container -->
  <div id="results_container"></div>


  // JAVASCRIPT (abstracted from a Prototype class, DO NOT use as-is)

  var selectMenu = $('select_element');
  var loadingElement = $('loading_element');
  var resultsContainer = $('results_container');

 // listen for keypress event (omitted other listeners and support test logic)
  this.selectMenu.addEventListener('keypress', this.__keyPressDetector, false);


 /* event callbacks */

 // Keypress listener

  __keyPressDetector:function(e){

    // if we are arrowing through the select, enable the loading element
    if(e.keyCode === 40 || e.keyCode === 38){
        if(e.target.id === 'select_element'){
            this.loadingElement.setAttribute('tabIndex','0');
        }
    }
    // if we tab off of the select, send focus to the loading element
    //  while it is fetching data
     else if(e.keyCode === 9){
        if(targ.id === 'select_element' && targ.options[targ.selectedIndex].value !== ''){            
            this.__changeStateDetector(e);

            this.loadingElement.focus();

        }   
    }
}

// content changer (also used for clicks)
__changeStateDetector:function(e){

    // only execute if there is a state change
    if(this.selectedState !== e.target.options[e.target.selectedIndex].rel){

       // get state name and file path
       var stateName = e.target.options[e.target.selectedIndex].rel;
       var stateFile = e.target.options[e.target.selectedIndex].value;

       // get the state file
       this.getStateFile(stateFile);

       this.selectedState = stateName;

    }
}

getStateFile:function(stateFile){
    new Ajax.Request(stateFile, {
        method: 'get',
        onSuccess:function(transport){      

            // insert markup into container
            var markup = transport.responseText;

            // NOTE: select which part of the fetched page you want to insert, 
            // this code was written to grab the whole page and sort later

            this.resultsContainer.update(markup);

            var timeout = setTimeout(function(){

                // focus on new content
               this.resultsContainer.focus();

            }.bind(this), 150);

        }.bind(this)
    });
}