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impress/src/lib/util.js

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+/**
+ * Common utility functions
+ *
+ * Copyright 2011-2012 Bartek Szopka (@bartaz)
+ * Henrik Ingo (c) 2016
+ * MIT License
+ */
+
+( function( document, window ) {
+    "use strict";
+    var roots = [];
+
+    var libraryFactory = function( rootId ) {
+        if ( roots[ rootId ] ) {
+            return roots[ rootId ];
+        }
+
+        // `$` returns first element for given CSS `selector` in the `context` of
+        // the given element or whole document.
+        var $ = function( selector, context ) {
+            context = context || document;
+            return context.querySelector( selector );
+        };
+
+        // `$$` return an array of elements for given CSS `selector` in the `context` of
+        // the given element or whole document.
+        var $$ = function( selector, context ) {
+            context = context || document;
+            return arrayify( context.querySelectorAll( selector ) );
+        };
+
+        // `arrayify` takes an array-like object and turns it into real Array
+        // to make all the Array.prototype goodness available.
+        var arrayify = function( a ) {
+            return [].slice.call( a );
+        };
+
+        // `byId` returns element with given `id` - you probably have guessed that ;)
+        var byId = function( id ) {
+            return document.getElementById( id );
+        };
+
+        // `getElementFromHash` returns an element located by id from hash part of
+        // window location.
+        var getElementFromHash = function() {
+
+            // Get id from url # by removing `#` or `#/` from the beginning,
+            // so both "fallback" `#slide-id` and "enhanced" `#/slide-id` will work
+            return byId( window.location.hash.replace( /^#\/?/, "" ) );
+        };
+
+        // Throttling function calls, by Remy Sharp
+        // http://remysharp.com/2010/07/21/throttling-function-calls/
+        var throttle = function( fn, delay ) {
+            var timer = null;
+            return function() {
+                var context = this, args = arguments;
+                window.clearTimeout( timer );
+                timer = window.setTimeout( function() {
+                    fn.apply( context, args );
+                }, delay );
+            };
+        };
+
+        // `toNumber` takes a value given as `numeric` parameter and tries to turn
+        // it into a number. If it is not possible it returns 0 (or other value
+        // given as `fallback`).
+        var toNumber = function( numeric, fallback ) {
+            return isNaN( numeric ) ? ( fallback || 0 ) : Number( numeric );
+        };
+
+        // `triggerEvent` builds a custom DOM event with given `eventName` and `detail` data
+        // and triggers it on element given as `el`.
+        var triggerEvent = function( el, eventName, detail ) {
+            var event = document.createEvent( "CustomEvent" );
+            event.initCustomEvent( eventName, true, true, detail );
+            el.dispatchEvent( event );
+        };
+
+        var lib = {
+            $: $,
+            $$: $$,
+            arrayify: arrayify,
+            byId: byId,
+            getElementFromHash: getElementFromHash,
+            throttle: throttle,
+            toNumber: toNumber,
+            triggerEvent: triggerEvent
+        };
+        roots[ rootId ] = lib;
+        return lib;
+    };
+
+    // Let impress core know about the existence of this library
+    window.impress.addLibraryFactory( { util: libraryFactory } );
+
+} )( document, window );