Let's say there is a feature on your website that only gets used 5% of the time. That feature requires some HTML, CSS, and JavaScript to work. So you decide that instead of having that HTML, CSS, and JavaScript on the page directly, you're going to Ajax that stuff in when the feature is about to be used.

We'll need to make three Ajax requests. Since we don't want to show anything to the user until the feature is ready to go (plus they all kinda rely on each other to work right) we need to wait for all three of them to be complete before proceeding.

What's the best way to do that?

Ajax calls in jQuery provide callbacks:

$.ajax({
      statusCode: {
        url: "/feature",
        success: function() {
          // Ajax success
        }
      }
    });

Or the "Deferred" way, this time using a shorthand $.get() method:

$.get("/feature/").done(function() {
      // Ajax success
    });

But we have three Ajax requests we're needing to perform, and we want to wait for all three of them to finish before doing anything, so it could get pretty gnarly in callback land:

// Get the HTML
    $.get("/feature/", function(html) {
    
      // Get the CSS
      $.get("/assets/feature.css", function(css) {
        
        // Get the JavaScript
        $.getScript("/assets/feature.js", function() {
    
           // All is ready now, so...
    
           // Add CSS to page
           $("<style />").html(css).appendTo("head");
    
           // Add HTML to page
           $("body").append(html);
    
        });
    
      });
    
    });

This successfully waits until everything is ready before adding anything to the page. So by the time the user sees anything, it's good to go. Perhaps that makes some of you feel nauseated, but I've done things that way before. At least it makes sense and works. The problem? It's slow.

One request ... wait to be done ... another request ... wait to be done ... another request ... wait to be done ... go.

It would be faster if we could do:

All three requests in parallel ... wait for all three to be done ... go.

We can use a bit of Deferred / Promises action to help here. I'm sure this is some JavaScript 101 stuff to some of you but this kind of thing eluded me for a long time and more complex Promises stuff still does.

In our simple use case, we can use jQuery's $.when() method, which takes a list of these "Deferred" objects (All jQuery Ajax methods return Deferred objects) and then provides a single callback.

$.when(
    
      // Deferred object (probably Ajax request),
    
      // Deferred object (probably Ajax request),
    
      // Deferred object (probably Ajax request)
    
    ).then(function() {
    
      // All have been resolved (or rejected), do your thing
    
    });

So our callback-hell can be rewritten like:

$.when(
      // Get the HTML
      $.get("/feature/", function(html) {
        globalStore.html = html;
      }),
    
      // Get the CSS
      $.get("/assets/feature.css", function(css) {
        globalStore.css = css;
      }),
    
      // Get the JS
      $.getScript("/assets/feature.js")
    
    ).then(function() {
    
      // All is ready now, so...
    
      // Add CSS to page
      $("<style />").html(globalStore.css).appendTo("head");
    
      // Add HTML to page
      $("body").append(globalStore.html);
    
    });

Another use case: mustard cutting

My use-case example above is a 5% feature. Keep the page lighter for the 95% of users who don't use the feature, and have it be a relatively quick add-on for those that do.

Another situation might be a cut-the-mustard situation where you add in additional features or content to a page in certain situations, as you decide. Perhaps do a matchMedia test on some media queries and determine the device's screen and capabilities are such that you're going to include some extra modules. Cool, do it up with some parallel Ajax calls!

Multiple Simultaneous Ajax Requests (with one callback) in jQuery is a post from CSS-Tricks

Is the death penalty slowly dying?

The United States is one of a dwindling number of nations that stills executes its citizens (thirty nine individuals in 2013). That job has recently gotten harder.

Since the death penalty was reinstated in 1976, the US has used a cocktail of three lethal drugs as its preferred method of execution.

However, since the Danish manufacturer of one of these drugs declared that it would no longer sell their product to US prisons, states have been scrambling for alternatives. 

The Missouri State Department of Corrections chose to substitute another drug, compounded pentobarbital, but a Federal judge blocked the pharmaceutical company’s attempt to supply the drug. The lawsuit declared that execution by compounded pentobarbital would cause  

“severe, unnecessary, lingering and ultimately inhumane pain.”

Faced with the same problem, Virginia attempted to make death by electric chair the default method of execution under state law. The bill failed earlier this week.

Finally, some states have abolished the death penalty altogether. Maryland outlawed the punishment last May, making it the eighteenth state to do so. Washington declared a state moratorium on Tuesday.

The death penalty inspires passion on both sides of the aisle, and with good cause.

Join the debate, and tell us: is it every okay for the government to kills its own citizens? And if somebody is going to die, does it matter how it happens?  

Education Professor of Practice Joan Shin has received the 2013 Ben Warren International House Trust Prize for her book Teaching Young Learners English (National Geographic Learning/Cengage Learning, 2013). Shin coauthored the book with JoAnn Crandall, Professor Emerita and former Director of the Language, Literacy and Culture Ph.D. program.

The prestigious award is given annually to the author or authors of the most outstanding work in the field of language teacher education. The Ben Warren International House Trust was created as a memorial to the work and life of Ben Warren, who was a leader in developing the world’s leading language teaching organization.

Shin’s book was published last year. It teaches English as a foreign language to young children and presents practical suggestions and best practices for teachers to engage young learners.

The award was announced in Barcelona, Spain on Saturday, February 8. You can read more about the announcement here. You can also find more information on Shin’s book series with National Geographic Learning here.