Created
September 30, 2013 15:56
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Functional Reactive Programming (I hope...)
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| <!DOCTYPE html> | |
| <html> | |
| <head> | |
| </head> | |
| <body> | |
| <input id="input1" type="range" min="0" max="100" value="50"></input> | |
| <input id="input2" type="range" min="0" max="100" value="50"></input> | |
| <div id="val"></div> | |
| <script> | |
| function ActiveValue(initValue) { | |
| this._callbacks = []; | |
| this._val = initValue; | |
| } | |
| ActiveValue.fromDOMInput = function (input) { | |
| var value = new ActiveValue(input.value); | |
| input.addEventListener('change', function (e) { | |
| value.set(e.target.value); | |
| }); | |
| return value; | |
| }; | |
| ActiveValue.create = function (val) { return new ActiveValue(val); }; | |
| ActiveValue.prototype.set = function (value) { | |
| this._val = value; | |
| this._callbacks.forEach(function (callback) { | |
| callback.fn.call(callback.ctx, value); | |
| }); | |
| return this; | |
| }; | |
| ActiveValue.prototype.get = function () { | |
| return this._val; | |
| }; | |
| ActiveValue.prototype.onValue = function (fn, ctx, doNotCallImmediatly) { | |
| this._callbacks.push({fn: fn, ctx: ctx || window}); | |
| if (!doNotCallImmediatly) { | |
| fn.call(ctx || window, this._val); | |
| } | |
| return this; | |
| }; | |
| ActiveValue.prototype.dependsOn = function (fn) { | |
| var deps = Array.prototype.slice.call(arguments, (typeof fn === 'function')); | |
| var fn = typeof fn === 'function' ? fn : function (a) { return a; } | |
| function onValue() { | |
| this.set(fn.apply(window, deps.map(function (dep) { return dep.get(); }))); | |
| } | |
| deps.forEach(function (dep) { | |
| dep.onValue(onValue.bind(this)); | |
| }, this); | |
| return this; | |
| }; | |
| var val = ActiveValue.create() | |
| .dependsOn( | |
| function (i1, i2) { | |
| return +i1 + +i2; | |
| }, | |
| ActiveValue.fromDOMInput(document.querySelector('#input1')), | |
| ActiveValue.fromDOMInput(document.querySelector('#input2')) | |
| ) | |
| .onValue(function (v) { | |
| document.querySelector('#val').innerHTML = v; | |
| }); | |
| </script> | |
| </body> | |
| </html> |
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