Demonstrate jQuery Deferred objects

deferredDemo.js

/*
Documentation for <a href="http://learn.jquery.com/code-organization/deferreds/">jQuery Deferred</a> objects.
<p>
<div>
    <button id="concur">Concurrent</button>
    <button id="sequent">Sequential</button>
</div>
<p>
<div id="result">
</div>
*/
// Sample code illustrating how to use jQuery Deferred/Promise objects

function log(msg)
{
    var s = $("#result").html();
    s += msg + "<br>\n";
    $("#result").html(s);
}

function clear() { $("#result").html(""); }

function delayThenDo( snooze )
{
    var deferd = $.Deferred();
    log("Starting " + snooze );
    setTimeout( function() { log("Timeout: " + snooze);
                             deferd.resolve(snooze+1);}, snooze);
    return deferd;
}

function finished(amount) { log("Promise result:" + amount); }

// Run all tasks concurrently, get result when last finishes
function testConcur() {
    clear();
    log("----Concurrent----");
    $.when( delayThenDo(1000),
            delayThenDo(1050),
            delayThenDo(1080) ).done( finished );
    log("...Exiting concurrent...");
}

// Run all tasks sequentially, output from previous feeds to next
function testSeq() {
    clear();
    log("----Sequential----");
    var completion = function (p) {finished(p); return delayThenDo( p )};
    var req = completion( 1000 );
    req.then( completion ).then( completion ).done( finished );
    log("...Exiting sequential...");
}

$("#concur").click( testConcur );
$("#sequent").click( testSeq );