Created
August 1, 2018 22:46
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Simple change detector example
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| <template> | |
| <ul href="#!" repeat.for="user of users"> | |
| <li> | |
| <input value.bind='user.firstName' /> <input value.bind='user.lastName' /> | |
| </li> | |
| </ul> | |
| </template> |
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| export class App { | |
| users = [ | |
| { id: 1, firstName: 'Rob', lastName: 'Eisenberg' }, | |
| { id: 2, firstName: 'Jeremy', lastName: 'Danyow' }, | |
| { id: 3, firstName: 'Matt', lastName: 'Broadst' }]; | |
| selectUser(userId) { | |
| let user = this.users.find(u => u.id == userId); | |
| user.state = 'active'; | |
| } | |
| activate() { | |
| var cd = new ChangeDetector(); | |
| cd.observe(this, 'users', (to,from,property)=>console.log({ to,from,property })); | |
| } | |
| } | |
| export class ChangeDetector { | |
| constructor() { | |
| } | |
| observe(target, property, callback, checkspersecond) { | |
| var subscription = { timer:{}, target, property, previous:{} }; | |
| subscription.timer = setInterval(() => this.compare(subscription, callback) , 1000/(checkspersecond || 7)); | |
| return () => { clearInterval(subscription.timer); } | |
| } | |
| compare(subscription:any, callback) { | |
| let s=subscription.target[subscription.property]; | |
| let path = 'this'; | |
| var diffs = this.finddiff(s, subscription.previous,0,path); | |
| if (diffs[0]) { callback(diffs[2], diffs[1], diffs[0] ); } | |
| subscription.previous = JSON.parse(JSON.stringify(s)) ; | |
| } | |
| finddiff = function(previous,current, depth, path){ | |
| let isarray = (current instanceof Array); | |
| for (var p in current) { | |
| if(typeof(current[p]) !== typeof(previous[p])) return [path+'.'+p,current[p] , previous[p]]; | |
| if((current[p]===null) !== (previous[p]===null)) return [path+'.'+p,current[p],previous[p]]; | |
| switch (typeof(current[p])) { | |
| case 'undefined': | |
| if (typeof(previous[p]) != 'undefined') return [path+'.'+p,undefined,previous[p]]; | |
| break; | |
| case 'object': | |
| if(current[p]!==null && previous[p]!==null | |
| && (current[p].constructor.toString() !== previous[p].constructor.toString())) | |
| return [path+'.'+p, current[p], previous[p]]; | |
| let nested = this.finddiff(previous[p],current[p], depth+1, path + (isarray ? '[' : '.') + p + (isarray ? ']' : '')); | |
| if(!!nested.length) return nested; | |
| break; | |
| case 'function': | |
| if (p != 'equals' && current[p].toString() != previous[p].toString()) return [path+'.'+p, current[p],previous[p]]; | |
| break; | |
| default: | |
| if (current[p] !== previous[p]) return [path+'.'+p, current[p], previous[p]]; | |
| } | |
| } | |
| return []; | |
| } | |
| } |
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| <!doctype html> | |
| <html> | |
| <head> | |
| <title>Aurelia</title> | |
| <meta name="viewport" content="width=device-width, initial-scale=1"> | |
| <link rel="stylesheet" href="styles.css"> | |
| </head> | |
| <body aurelia-app> | |
| <h1>Loading...</h1> | |
| <script src="https://cdn.rawgit.com/jdanyow/aurelia-bundle/v1.0.3/jspm_packages/system.js"></script> | |
| <script src="https://cdn.rawgit.com/jdanyow/aurelia-bundle/v1.0.3/config.js"></script> | |
| <script> | |
| System.import('aurelia-bootstrapper'); | |
| </script> | |
| </body> | |
| </html> |
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| a { | |
| display: block; | |
| } | |
| a:link { | |
| color: black; | |
| text-decoration: none; | |
| } | |
| .collection-item | |
| { | |
| background: lightgray; | |
| } | |
| /* since you set background property on .collection-item, this style must come after .collection-item otherwise it's not applied */ | |
| .active { | |
| background: blue; | |
| } |
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