jquery - Return true if key is down in javascript loop? - Stack Overflow

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I want to add a condition inside a loop that tests if the right arrow is pressed and if it is move a div a bit to the right. However I don't know how to check for they keydown.

I'm using a code to do it but it is really long and I'm sure there is an shorter way to do it.

This is the code:

    <div id="char"></div>
    <script>
    setInterval(function() {

// here it should check if RIGHT (keycode 39) is down and move char 10px to the right if it is;

    }, 20);
    </script>

How can I check for keydown inside the loop? Btw I'm also using jQuery on the site.

Thanks

I want to add a condition inside a loop that tests if the right arrow is pressed and if it is move a div a bit to the right. However I don't know how to check for they keydown.

I'm using a code to do it but it is really long and I'm sure there is an shorter way to do it.

This is the code:

    <div id="char"></div>
    <script>
    setInterval(function() {

// here it should check if RIGHT (keycode 39) is down and move char 10px to the right if it is;

    }, 20);
    </script>

How can I check for keydown inside the loop? Btw I'm also using jQuery on the site.

Thanks

• javascript
• jquery

Share Improve this question Follow edited May 23, 2011 at 21:34 lisovaccaro asked May 23, 2011 at 21:21 lisovaccarolisovaccaro 34.1k9999 gold badges271271 silver badges423423 bronze badges 3

• 1 are you using any libraries like jQuery or just raw JS? – Oscar Godson Commented May 23, 2011 at 21:22
• Similar: stackoverflow./questions/2445613/… – spanky Commented May 23, 2011 at 21:38
• See my updated answer... added jQuery too if you want – Oscar Godson Commented May 23, 2011 at 21:38

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3 Answers 3

Sorted by: Reset to default 4

Here ya go in raw JS you'd do something like this (press Preview then hold down w):

http://jsbin./odalo3/edit

var isPressed = false;

var keydown = function(e){ 
  if(e.keyCode == 87){
    isPressed = true;
  }
}
var keyup = function(e){
    isPressed = false;
}

document.addEventListener("keydown",keydown,false);
document.addEventListener("keyup",keyup,false);

setInterval(function(){
  if(isPressed){
    document.getElementById('hello').innerHTML = document.getElementById('hello').innerHTML+', pressed';
  } 
},100)

UPDATE

If you are using jQuery you can change the eventListeners to:

$(window).keydown(function(e){
   if(e.keyCode == 87){
     isPressed = true;
   }
})
.keyup(function(e){
  isPressed = false;
})

And delete these lines:

var keydown = function(e){ 
  if(e.keyCode == 87){
    isPressed = true;
  }
}
var keyup = function(e){
    isPressed = false;
}

document.addEventListener("keydown",keydown,false);
document.addEventListener("keyup",keyup,false);

But it's the same thing.

Use jQuery and keydown:

<div id="char"></div>
<script>
$(document).keydown(function(e){
    if(e.keyCode == 39){
          //do something
        $("#char").animate({'left':'+=10'}, 1);
     }
})
</script>

Fiddle: http://jsfiddle/maniator/zXeXt/

Create a flag var pressed; and set it to true or false in keyPress event; then check it inside the loop

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