Below is the code to test when a keydown and keyup code are triggered. The canvas shows a message when the left arrow key is pressed and then it is not pressed.
You need to know when a key is pressed when a character is to be moved on the screen. Just copy and paste the code into a empty file and save it as a htm file. Then double click on it to see it in action. This code has been tested in ie9.
<!DOCTYPE = html> <html><body> <canvas id="myCanvas" width="300" height="150" style="border:1px solid #d3d3d3;"> Use different browser. </canvas> <script> var c=document.getElementById("myCanvas"); var ctx=c.getContext("2d"); var test="Left arrow key is not pressed."; gameloop=setInterval(doGameLoop,16); window.addEventListener("keydown",kd,true); window.addEventListener("keyup",ku,true); function doGameLoop(){ ctx.clearRect(0,0,c.width,c.height); ctx.fillText(test,10,10); } function kd(evt){ if(evt.keyCode==37){ test="Left arrow key is pressed."; } } function ku(evt){ if(evt.keyCode==37){ test="Left arrow key is not pressed."; } } </script></body></html>
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