html button and javascript code

Question

Ok. I make a program for calculating the power of 2. I have the html code . But i describe it for you first. There is one input with id='inputin' and below there is a button. In the input you write a number . This number will be the exponent of two and after you push the button it appears a console.log window with the result

here the html :

<div id='main'>
    <input type="number" name="power2" placeholder='Enter the power' id='inputin'><br/>
    <button id="submit" onclick="binaryS()">Do it!</button>

    </div>

and the javascript:

binaryS = function() {
x = document.getElementById("inputin").value;
y=1;
for(i=1;i<=x;i++) {
    y=y*2;
}
console.log (y);
};

Why it doesnt work? Any help? and if you could suggest instead of an ugly console.log window how can i appear it in a new div somewhere in the page? Thnx

Do you understand that console.log() doesn't open a window automatically? You have to view the log manually using Developer Tools. — Barmar
– Barmar, Commented Jun 28, 2013 at 19:29

dsgriffin · Accepted Answer · 2013-06-28 19:34:19Z

7

Your JavaScript should be:

function binaryS() {
   var x = document.getElementById("inputin").value;
   document.getElementById("outputValue").innerHTML = Math.pow(2,x);
}

Place the following somewhere on your page for the display:

<div id="outputValue">Result</div>

edited Jun 28, 2013 at 19:34

dsgriffin

68.8k17 gold badges141 silver badges139 bronze badges

answered Jun 28, 2013 at 19:31

user1641172

Sign up to request clarification or add additional context in comments.

2 Comments

GolezTrol Over a year ago

+1 Beat me to it when I was building this fiddle, which does essentially the same, only with span and innerText. And without using math. :p

user1641172 Over a year ago

That's my first real answer :D Thanks to this lovely site i rarely have questions to ask!

Learner · Accepted Answer · 2013-06-28 19:31:41Z

1

Try this function:

function nearestPow2(){
  return Math.pow(2, Math.round(Math.log(document.getElementById("inputin").value;) / Math.log(2))); 
}

Ref: http://weblog.bocoup.com/find-the-closest-power-of-2-with-javascript/

answered Jun 28, 2013 at 19:31

Learner

4,0047 gold badges32 silver badges45 bronze badges

Comments

user2377782 · Accepted Answer · 2013-06-28 19:36:35Z

Without getting into details, your code is working. I have made a single html page to demonstrate it:

<html>
    <head>
        <script type="application/x-javascript">
            binaryS = function() {
                x = document.getElementById("inputin").value;
                y=1;
                for(i=1;i<=x;i++) {
                    y=y*2;
                }
                document.getElementById('result').innerHTML = y
            };
        </script>
    </head>
    <body>
        <div id='main'>
            <input type="number" name="power2" placeholder='Enter the power' id='inputin'><br/>
            <button id="submit" onclick="binaryS()">Do it!</button>
        </div>
        <div id="result" ></div>
    </body>
</html>

I also would suggest you using Math.pow instead of a custom math calculation:

Math.pow( 2, parseInt(document.getElementById("inputin").value));

Collectives™ on Stack Overflow

html button and javascript code

3 Answers 3

2 Comments

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

2 Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related