Basic change detection scope and directives implemented in one page of code, basically it’s Angular without Angular!
Video: https://www.youtube.com/watch?v=Mk2WwSxK218
Demo: http://stevenhollidge.com/blog-source-code/angular-from-scratch
Code:
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| <html> | |
| <head> | |
| <title>Angular From Scratch</title> | |
| <style> | |
| body { | |
| height: 100%; | |
| margin: 0; | |
| background-image: url('slides/img/whitepage.jpg'); | |
| display: flex; | |
| flex-direction: column; | |
| justify-content: center; | |
| } | |
| h1, h2 { | |
| font-family: 'Cherry Cream Soda', cursive; | |
| font-size: 4em; | |
| text-align: center; | |
| align-items: center; | |
| background-color: rgba(0, 0, 0, 0.5); | |
| color: white; | |
| padding: .2em; | |
| margin: 0; | |
| } | |
| input { | |
| font-size: .5em; | |
| margin: .5em; | |
| border-radius: .2em; | |
| border: none; | |
| } | |
| </style> | |
| </head> | |
| <body> | |
| <h1 ng-bind="hello">hello</h1> | |
| <h2><input type="text" ng-model="hello"></h2> | |
| <script> | |
| 'use strict'; | |
| // scope | |
| var Scope = function() { | |
| this.$$watchers = []; | |
| this.$watch = function(watcherFn, listenerFn) { | |
| this.$$watchers.push({ | |
| watcherFn: watcherFn, | |
| listenerFn: listenerFn | |
| }); | |
| }; | |
| this.$digest = function() { | |
| this.$$watchers.forEach(function(watcher) { | |
| var newValue = watcher.watcherFn(); | |
| var oldValue = watcher.last; | |
| if(newValue !== oldValue) { | |
| watcher.listenerFn(newValue, oldValue); | |
| watcher.last = newValue; | |
| } | |
| }); | |
| }; | |
| this.$apply = function(exprFn) { | |
| try { | |
| exprFn(); | |
| } finally { | |
| this.$digest(); | |
| } | |
| }; | |
| }; | |
| var $scope = new Scope(); | |
| // compiler | |
| var $$directives = { | |
| 'ng-bind': function($scope, $element, $attributes) { | |
| $scope.$watch(function() { | |
| return $scope[$attributes['ng-bind'].value]; | |
| }, function(newValue) { | |
| $element.innerHTML = newValue; | |
| }); | |
| }, | |
| 'ng-model': function($scope, $element, $attributes) { | |
| $scope.$watch(function() { | |
| return $scope[$attributes['ng-model'].value]; | |
| }, function(newValue) { | |
| $element.value = newValue; | |
| }); | |
| $element.addEventListener('keyup', function() { | |
| $scope.$apply(function() { | |
| $scope[$attributes['ng-model'].value] = $element.value; | |
| }); | |
| }); | |
| } | |
| }; | |
| var $compile = function(element, $scope) { | |
| Array.prototype.forEach.call(element.children, function(child) { | |
| $compile(child, $scope); | |
| }); | |
| Array.prototype.forEach.call(element.attributes, function(attribute) { | |
| var directive = $$directives[attribute.name]; | |
| if(directive) { | |
| directive($scope, element, element.attributes); | |
| } | |
| }); | |
| }; | |
| $compile(document.body, $scope); | |
| // tests & logs | |
| $scope.hello = 'Hello ng-Europe'; | |
| $scope.$watch(function() { | |
| return $scope.hello; | |
| }, function(newValue, oldValue) { | |
| console.log('hello changed from', oldValue, 'to', newValue); | |
| }); | |
| </script> | |
| </body> | |
| </html> |
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