can/demos/can-view-callbacks/fade_in_when.html

MIT-licensed, client-side, JavaScript framework that makes building rich web applications easy.

<link rel="stylesheet" href="../../node_modules/jquery-ui/themes/base/all.css" />
<script type="text/javascript" src="//code.jquery.com/jquery-3.3.1.min.js"></script>
<script type="text/javascript" src="//code.jquery.com/ui/1.12.1/jquery-ui.js"></script>
<div id="app"></div>
<script type="text/stache" id="demo-html">
<button toggle="showing">
	{{# if(showing) }}Hide{{ else }}Show{{/ if }} more info
</button>
<div fade-in-when="showing">
	Here is more info!
</div>
</script>

<script src="../../node_modules/steal/steal.js" dev-bundle main="@empty">
import { DefineList, DefineMap, domEvents, SimpleObservable,
	stache, stacheBindings, viewCallbacks } from "can";

viewCallbacks.attr("toggle", function(el, attrData) {
	var attrValue = el.getAttribute("toggle");
	var toggleCompute = attrData.scope.compute(attrValue);

	$(el).click(function() {
		toggleCompute( ! toggleCompute() );
	});
});

viewCallbacks.attr("fade-in-when", function(el, attrData) {
	var attrValue = el.getAttribute("fade-in-when");
	var fadeInCompute = attrData.scope.compute(attrValue);

	// handler for when the observable changes
	var handler = function(event, newVal, oldVal) {
		if (newVal && !oldVal) {
			$(el).fadeIn("slow")
		} else if (!newVal) {
			$(el).hide()
		}
	};

	fadeInCompute.on("change", handler);

	handler(fadeInCompute());

	domEvents.addEventListener(el, "removed", function() {
		fadeInCompute.off("change", handler);
	});
});

var template = stache.from('demo-html');

$("#app").html( template({
	showing: new SimpleObservable(false)
}) );
</script>