<link href="{{componentAssets}}/node.css" rel="stylesheet" type="text/css">

<div class="intro">

<p>This example demonstrates how to use multiple NodeList features to build a simple game.</p>

</div>

<div class="example">

{{>ducks-source}}

</div>

<h2>The HTML</h2>

```

{{>ducks-html}}

```

<h2>YUI Instance</h2>

<p>

The `use` statement doesn't include `node` because it's loaded as a requirement of transition.

</p>

```

YUI().use('transition', 'button', function(Y){

// code goes here

});

```

<h2>Setting Vars</h2>

<p>

The variable `ducks` is used for easily manipulating all the ducks at once.

We'll display various duck comments from the array `squawkTextArr` on a rotating basis.

</p>

```

var ducks = Y.all('.duck-row li'),

ducksRemaining = 10, // value for UI display

squawkTextIndex = 0, // index in the squawkTextArr to use next

squawkTextArr = [ // duck comments

'#@&~*Q!',

'Hey!?',

'911 on U!',

"U&nbsp;fly's&nbsp;down",

'duck&nbsp;pile!',

'Ricochets&nbsp;kill!',

'how&nbsp;sporting.',

"shoe's&nbsp;untied"

];

```

<h2>Initializing the Ducks</h2>

<p>

Repetitive markup is added with the `.append()` method to all the ducks in the `NodeList`.

This keeps the original markup simple and clear.

</p>

```

// append the same content for each duck <li>

ducks.append('<img src="../assets/node/images/duck.png"/><div class="squawk"><div class="text">#@&~*Q!</div><div class="small-squawk-bubble"></div></div>');

```

<p>

All the ducks in the `NodeList` are given the `set-up` class with the `.addClass()` method.

This class is found on any duck that has the state of being set up, as opposed to being knocked down.

</p>

```

// give them all the set-up state class

ducks.addClass('set-up');

```

<p>

This state could be a Boolean property, but it's handy as a class,

because a `NodeList` can be made containing the squawks of all "set up" ducks in this way,

`squawks = Y.all('.duck-row .set-up .squawk');`

as we'll see in the `makeDucksSquawk` function.

</p>

<h2>Making the Ducks Swim</h2>

<p>

This uses `transition` to make the ducks swim right to left

</p>

```

// this makes the ducks move from right to left.

// When the duck on the far left disappears from view,

// it's added to the far right end of the row.

var makeDucksSwim = function () {

var frontDuck;

// move the duck row to the left one duck space over 2 seconds

Y.one('.duck-row').transition({

easing: 'linear',

left: '-119px',

duration: 2

}, function () { // when the row finishes its right to left transition...

// remove the first duck on the left

// which has trasitioned out of view

frontDuck = Y.one('.duck-row li').remove();

// append the removed first duck onto the right end

Y.one('.duck-row').appendChild(frontDuck);

// set the position for the next makeDucksSwim()

Y.one('.duck-row').setStyle('left', '10px');

// if there are ducks remaining, make them swim again

if (ducksRemaining > 0) {

makeDucksSwim();

}

});

}

makeDucksSwim(); // this initializes the ducks swimming

```

<h2>Click Event Handler</h2>

<p>

</p>

```

// handles a click on a duck

var duckClick = function(e) {

var squawks;

// remove the squawk belonging to the duck that was clicked

e.currentTarget.one('.squawk').setStyles({'top': '-400px', 'opacity': '1'});

// makes the ducks appear to lay back when clicked

e.target.transition({

duration: 0.2,

height: '3px',

width: '133px'

});

// the clicked duck will no longer have the 'set-up' class/state

e.currentTarget.removeClass('set-up');

makeDucksSquawk(); // makes the ducks squawk

updateDucksRemaining(); // update the number of ducks still set up

};

```

<h2>Squawking Ducks</h2>

<p>

</p>

```

// this makes the duck's squawks show and hide and get various text

var makeDucksSquawk = function(){

squawks = Y.all('.duck-row .set-up .squawk'); // a NodeList of the squawks of set-up ducks

if (Y.one('#show-attitude')._node.checked) { // only have ducks squawk if the checkbox is checked

// fill voice bubbles with next text string

Y.all('.duck-row .set-up .squawk .text').setContent(squawkTextArr[squawkTextIndex]);

// increment the index to get the next squawk text

squawkTextIndex = (squawkTextIndex += 1) % (squawkTextArr.length);

squawks.transition({

top: {

delay: 0.5,

value: '0px', // drop squawks into position from hidden

duration: 0 // instant position change

},

opacity: { // fade out

delay: 3.0,

duration: 0.3,

value: 0

}

}, function(e){

// after squawks are faded out,

// move them to hidden position and set opacity to 1 again

squawks.setStyles({'top': '-400px', 'opacity': '1'});

});

}

}

```

<h2>Reset and Ducks Remaining</h2>

```

// This resets all ducks, "ducks remaining" counters, and row position

// make the duck images full height

// start them swimming

var reset = function() {

Y.all('.duck-row li img').setStyle('height', '55px');

Y.all('.duck-row li').addClass('set-up');

updateDucksRemaining();

makeDucksSwim();

}

// counts the ducks remaining, and updates the UI counter display

var updateDucksRemaining = function() {

ducksRemaining = Y.all('.gallery li.set-up').size();

Y.one('.ducks-remain').setContent(ducksRemaining);

}

```

<h2>Prefer `node.delegate()` over `nodelist.on()`</h2>

<p>Sometimes you need to create individual subscriptions for each Node in a

NodeList, but usually it's preferable to use

<a href="node-evt-delegation.html">event delegation</a> as shown in this example.</p>

<h2>Listeners</h2>

<p>

</p>

```

// listeners

Y.one('.duck-row').delegate('click', duckClick, 'li');

Y.one('#button-reset').on('click', reset);

```

<h2>Complete Ducks Example Source</h2>

```

{{>ducks-source}}

```