个回答

• Oneleven

  2018-05-30 10:09:51

  你的时间小时超过两位数了

  0

• 性别男爱好女

  2018-04-18 18:23:44

  你可以检查下，你digit文件有没有，正不正确，如果正确就检查下你时间是否获取到了

  0

• 慕无忌0244622

  2018-04-09 22:24:23

  我也遇到过同样问题了，你解决了吗

  0

• JackeyT

  2018-03-29 11:12:20

  digit是数字矩阵，老师单独定义在另外一个js文件的，你也可以在本段js中自己定义

  0

• 慕_斯_用_户

  2018-03-25 14:51:12

  不能读取属性的长度定义

  
  

  0

• 月吖阿

  2018-03-25 14:50:18

  var WIDOW_WIDTH=1024;
  var WIDTH_HEIGHT=768;
  var RADIUS=8;
  var MARGIN_LEFT=30;
  var MARGIN_TOP=60;
  
  const endTime=new Date(2018,4,26,17,39,56);
  var curShowTimeSeconds=0;
  
  window.onload=function(){
  	var canvas =document.getElementById("canvas");
  	var context =canvas.getContext("2d");
  	
  	canvas.width=WIDOW_WIDTH;
  	canvas.height=WIDTH_HEIGHT;
  	
  	curShowTimeSeconds=getCurrentShowTimeSeconds()
  	
  	render(context)
  }
  
  function getCurrentShowTimeSeconds(){
  	var curTime=new Date();
  	var ret=endTime.getTime()-curTime.getTime();
  	ret=Math.round(ret/1000)
  	return ret>=0?ret:0;
  }
  
  function render(cxt){
  	
  	
  	var hours=parseInt(curShowTimeSeconds/3600);
  	var minutes=parseInt((curShowTimeSeconds=hours*3600)/60);
  	var seconds=curShowTimeSeconds%60;
  	
  	
  	renderDigit(MARGIN_LEFT,MARGIN_TOP,parseInt(hours/10),cxt);
  	renderDigit(MARGIN_LEFT+15*(RADIUS+1),MARGIN_TOP,parseInt(hours%10),cxt);
  	renderDigit(MARGIN_LEFT+30*(RADIUS+1),MARGIN_TOP,10,cxt);
  	renderDigit(MARGIN_LEFT+39*(RADIUS+1),MARGIN_TOP,parseInt(minutes/10),cxt);
  	renderDigit(MARGIN_LEFT+54*(RADIUS+1),MARGIN_TOP,parseInt(minutes%10),cxt);
  	renderDigit(MARGIN_LEFT+69*(RADIUS+1),MARGIN_TOP,10,cxt);
  	renderDigit(MARGIN_LEFT+78*(RADIUS+1),MARGIN_TOP,parseInt(seconds/10),cxt);
  	renderDigit(MARGIN_LEFT+93*(RADIUS+1),MARGIN_TOP,parseInt(seconds%10),cxt)
  }
  
  function renderDigit(x,y,num,cxt){
  	cxt.fillStyle="black";
  	for(var i=0;i<digit[num].length;i++)
  		for(var j=0;j<digit[num][i].length;j++)
  		if(digit[num][i][j]==1){
  			cxt.beginPath();
  			cxt.arc(x+j*2*(RADIUS+1)+(RADIUS+1),y+i*2*(RADIUS+1)+(RADIUS+1),RADIUS,0,2*Math.PI);
  			cxt.closePath();
  			
  			cxt.fill()
  		}
  }

  [Web浏览器] "Uncaught TypeError: Cannot read property 'length' of undefined" /canvas/js/countdown.js (49)

  0