document.keydown = function(event){ var event = event || window.event; var keyCode = event.keyCode || event.which; switch(keyCode){ case 37: if(speedX == 0){ speedX = -1; speedY = 0; } break; case 38: if(speedY == 0){ speedX = 0; speedY = -1; } break; case 39: if (speedX == 0){ speedX = 1; speedY = 0; } break; case 40: if(speedY == 0){ speedX = 0; speedY = 1; } break; default: return; break; } boxMove(); }
?
控制臺沒有報錯，元素獲取也沒有問題
但是用下面這段就可以，為什么會這樣
document.addEventListener("keydown",function(event){ var event = event || window.event; var keyCode = event.keyCode || event.which; switch(keyCode){ case 37: if(speedX == 0){ speedX = -1; speedY = 0; } break; case 38: if(speedY == 0){ speedX = 0; speedY = -1; } break; case 39: if(speedX == 0){ speedX = 1; speedY = 0; } break; case 40: if(speedY == 0){ speedX = 0; speedY = 1; } break; default: return; break; } boxMove();},false);
想通過按鍵控制一個塊移動，這段代碼為何不起作用
慕碼人8056858
2018-12-06 17:04:37
