Angular

gistfile1.html

<script src="http://code.angularjs.org/angular-0.9.16.min.js" ng:autobind></script>
<script>
    var SERVICE_URL = "http://blockexplorer.com/q/getdifficulty";
    function CalculatorController($xhr) {
        this.integer = /^\d+$/;
        this.fraction = /^\d+\.*\d*$/;
        this.fetch = function() {
            var self = this;
            $xhr('', SERVICE_URL, function(code, response) {
                self.difficulty = response;
            });
            this.hashtime = function() { return Math.round(this.difficulty * Math.pow(2, 32) / (this.hashrate * 1000))/(3600*24) };
            this.opex = function() { return this.time*24 * this.electricity * this.power / 1000 };
            this.income = function() { return Math.round(this.rate * this.btcperblock * this.time / this.hashtime()); };
            this.profit = function() { return this.income() - this.opex() - this.capex };
        };
    }
</script>
<div ng:controller="CalculatorController">
    <table>
        <tr>
            <td>Difficulty:</td>
            <td><input type="text" size="8" name="difficulty" value="880000" ng:required ng:validate="regexp:integer"/></td>
            <td><button ng:click="fetch()">Fetch</button></td>
        </tr>
        <tr>
            <td>Hash rate:</td>
            <td><input type="text" size="8" name="hashrate" value="225000" ng:required ng:validate="regexp:integer"/></td>
            <td>khash/s</td>
        </tr>
        <tr>
            <td>Time frame:</td>
            <td><input type="text" size="8" name="time" value="30" ng:required ng:validate="regexp:integer"/></td>
            <td>days</td>
        </tr>
        <tr>
            <td>Cost of hardware:</td>
            <td><input type="text" size="8" name="capex" value="0" ng:required ng:validate="regexp:fraction"/></td>
            <td>USD</td>
        </tr>
        <tr>
            <td>Cost of electricity:</td>
            <td><input type="text" size="8" name="electricity" value="0.15" ng:required ng:validate="regexp:fraction"/></td>
            <td>USD/kWh</td>
        </tr>
        <tr>
            <td>Power consumption:</td>
            <td><input type="text" size="8" name="power" value="500" ng:required ng:validate="regexp:integer"/></td>
            <td>W</td>
        </tr>
        <tr>
            <td>Coins generated per block:</td>
            <td><input type="text" size="8" name="btcperblock" value="50" ng:required ng:validate="regexp:integer"/></td>
            <td>BTC/block</td>
        </tr>
        <tr>
            <td>Exchange rate:</td>
            <td><input type="text" size="8" name="rate" value="20" ng:required ng:validate="regexp:fraction"/></td>
            <td>USD/BTC</td>
        </tr>
        <tr>
            <td>Operational cost:</td>
            <td>{{opex}}</td>
            <td>USD/{{time}} days</td>
        </tr>
        <tr>
            <td>Hash time:</td>
            <td>{{hashtime}}</td>
            <td>days</td>
        </tr>
        <tr>
            <td>Income:</td>
            <td>{{income}}</td>
            <td>USD</td>
        </tr>
        <tr>
            <td>Profit:</td>
            <td>{{profit}}</td>
            <td>USD/{{time}} days</td>
        </tr>
    </table>
</div>