basic feature detection framework idea

phiggins42 · Jul 25, 2010 · 479c19a · 479c19a
1 parent 448b672
commit 479c19a
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diff --git a/feature.js b/feature.js
@@ -0,0 +1,74 @@
+dojo.provide("plugd.feature");
+
+(function(d){
+
+	var tests = {}, htmlelm = d.doc.documentElement;
+
+	d.feature = function(test){
+		// summary: Returns a boolean synchronously to test something.
+		//
+		// test: String|Array
+		//		A string get of something to test.
+		//		If an array, all conditions in the array must pass
+		//		each item in the array is to be a string test name
+		//
+		// example:
+		//	|	if(dojo.feature("opacity")){ /* use png */ }
+		//
+		// example:
+		//	|	if(dojo.feature(["opacity", "css3", "placeholder"])){
+		//	|		// enviroment has opacity, css3 and input placeholder=""
+		//	|	}
+		//
+		// returns: Boolean
+		//		Or undefined if no test has been created for a given testname
+
+		// multi means all must pass to be true:
+		if(d.isArray(test)){ return d.every(test, d.feature); }
+
+		// single test consideration:
+		if(tests[test] !== true || tests[test] !== false){
+			if(d.isFunction(tests[test])){
+				tests[test] = !!tests[test]();
+				// add a class name to the `html` element for CSS uses
+				d.addClass(htmlelm, (!tests[test] ? "no-" : "") + test); 
+			}
+		}
+
+		// always return something:
+		return tests[test];
+	}
+
+	d.feature.test = function(test, testcb, now){
+		// summary: Add a test condition to this enviroment. key is the testname, 
+		// testcb: Function|Boolean
+		//		If a function, will be run once ever to do a test. the return of
+		//		this function kills the function and returns a boolean.
+		// now: Boolean?
+		//		Immediately force the execution of this test
+		// example:
+		//	|	d.feature.test("opacity", function(){
+		//	|		// add a node. calculate some styles. determine in here if
+		//	|		// this enviorment supports "opacity", whatever the hell that means
+		//	|		return true;
+		//	|	});
+		//
+		// example:
+		//	Possible to just set a boolean for the test if you've already run it
+		//	though no class name will be applied to the `html` element. 
+		//	|	d.feature.test("js-runs", true); 
+		//
+		// example:
+		//	Force the immediate processing of a passed test: d.feature("somethingfun")
+		//	will always return false, but only execute once, immediately upon registration
+		//	passing a function will trigger `html` class name addition
+		//	|	d.feature.test("somethingfun", function(){ return false; }, true);
+
+		tests[test] = testcb;
+		now && d.feature(test);
+	}
+
+	// basic test: js is always enabled if we've run, clearly.
+	d.feature.test("js", function(){ return true; }, true);
+
+})(dojo);
diff --git a/tests/base.js b/tests/base.js
@@ -6,4 +6,5 @@ if(dojo.isBrowser){
 	doh.registerUrl("plugd.tests.node", dojo.moduleUrl("plugd.tests", "node.html"));
 	doh.registerUrl("plugd.tests.keys", dojo.moduleUrl("plugd.tests", "keys.html"));
 	doh.registerUrl("plugd.tests.data", dojo.moduleUrl("plugd.tests", "data.html"));
+	doh.registerUrl("plugd.tests.feature", dojo.moduleUrl("plugd.tests", "feature.html"));
 }
diff --git a/tests/feature.html b/tests/feature.html
@@ -0,0 +1,32 @@
+<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
+	"http://www.w3.org/TR/html4/strict.dtd">
+<html>
+	<head>
+		<title>Testing dojo.feature</title>
+
+		<script type="text/javascript" src="../../dojo/dojo.js" djConfig="isDebug: true"></script>
+
+		<script type="text/javascript">
+			dojo.require("doh.runner");
+			dojo.require("plugd.feature");
+
+			dojo.addOnLoad(function(){
+
+				var html = dojo.doc.documentElement;
+
+				doh.register("t", 
+					[
+
+						function jsclass(t){
+						    // js test always runs
+							t.t(dojo.hasClass(html, "js"));
+						}
+					]
+				);
+				doh.run();
+			});
+		</script>
+	</head>
+	<body>
+	</body>
+</html>