Created
September 9, 2012 07:34
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Moving element with key control
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| <!DOCTYPE html> | |
| <html> | |
| <head> | |
| <script src="http://code.jquery.com/jquery-1.7.2.min.js"></script> | |
| <meta charset=utf-8 /> | |
| <title>JS Bin</title> | |
| <style> | |
| #arena { | |
| position: relative; | |
| width: 400px; | |
| height: 400px; | |
| border: 1px solid #333; | |
| } | |
| #box { | |
| position: absolute; | |
| left: 0; | |
| top: 0; | |
| width: 80px; | |
| height: 80px; | |
| background-color: green; | |
| } | |
| </style> | |
| </head> | |
| <body> | |
| <div id="arena"> | |
| <div id="box"></div> | |
| </div> | |
| <script> | |
| $(function() { | |
| var arena = $('#arena'); | |
| var box = $('#box'); | |
| box.movingLeft = false; | |
| box.movingRight = false; | |
| box.movingUp = false; | |
| box.movingDown = false; | |
| var KEY_LEFT = 37, | |
| KEY_RIGHT = 39, | |
| KEY_UP = 38, | |
| KEY_DOWN = 40; | |
| var velocity = 25; | |
| setInterval(draw, 25); | |
| function draw() { | |
| var x = parseInt( box.css('left') ); | |
| var y = parseInt( box.css('top') ); | |
| //console.log('x: ' + x + ', y: ' + y); | |
| if ( box.movingLeft ) x -= velocity; | |
| else if ( box.movingRight ) x += velocity; | |
| if ( box.movingUp ) y -= velocity; | |
| else if ( box.movingDown ) y += velocity; | |
| // check bounded arena on horizontal axis | |
| if ( x <= 0 ) x = 0; | |
| if ( x + box.width() > arena.width() ) { | |
| x = arena.width() - box.width(); | |
| } | |
| // check bounded arena on vertical axis | |
| if ( y <= 0 ) y = 0; | |
| if ( y + box.height() > arena.height() ) { | |
| y = arena.height() - box.height(); | |
| } | |
| // update the position | |
| box.css({'left': x}); | |
| box.css({'top': y}); | |
| } | |
| $(document).keydown(onKeyDown); | |
| $(document).keyup(onKeyUp); | |
| function onKeyDown(e) { | |
| if (e.keyCode === KEY_LEFT) box.movingLeft = true; | |
| else if (e.keyCode === KEY_RIGHT) box.movingRight = true; | |
| if (e.keyCode === KEY_UP) box.movingUp = true; | |
| else if (e.keyCode === KEY_DOWN) box.movingDown = true; | |
| } | |
| function onKeyUp(e) { | |
| if (e.keyCode === KEY_LEFT) box.movingLeft = false; | |
| else if (e.keyCode === KEY_RIGHT) box.movingRight = false; | |
| if (e.keyCode === KEY_UP) box.movingUp = false; | |
| else if (e.keyCode === KEY_DOWN) box.movingDown = false; | |
| } | |
| }); | |
| </script> | |
| </body> | |
| </html> |
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