Created
April 15, 2014 06:56
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| <!DOCTYPE html> | |
| <html> | |
| <head> | |
| <meta charset="utf-8"> | |
| <title>Naive promise implementation</title> | |
| </head> | |
| <body> | |
| <button id="a-button">Click</button> | |
| </body> | |
| </html> |
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| function Promise(){ | |
| this.callbacks = []; | |
| this.resolved = false; | |
| } | |
| Promise.prototype.then = function(callback){ | |
| if(this.resolved){ | |
| callback(this.data); | |
| } | |
| else{ | |
| this.callbacks.push(callback); | |
| } | |
| } | |
| Promise.prototype.resolve = function(data){ | |
| this.data = data; | |
| var callback; | |
| for(var i = 0; i < this.callbacks.length; i++){ | |
| callback = this.callbacks[i]; | |
| callback(data); | |
| } | |
| this.resolved = true; | |
| } | |
| // =========== | |
| function doStuff(){ | |
| var promise = new Promise(); | |
| setTimeout(function(){ | |
| promise.resolve('timed out message'); | |
| }, 6000); | |
| return promise; | |
| } | |
| var promise = doStuff(); | |
| promise.then(function(message){ | |
| console.log(message); | |
| }); | |
| // =========== | |
| var btn = document.getElementById('a-button'); | |
| btn.addEventListener('click', function(e){ | |
| promise.then(function(message){ | |
| console.log('from click event'); | |
| console.log(message); | |
| }); | |
| }); |
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