引进 jquery

这是使用jq写的js,所以前提一定要引进jq的包,不然无法使用

html 部分

<body> 		 <canvas id="canvas" width="100" height="30"></canvas> 	</body> 

css 部分

 		.input-val { 			  width: 200px; 			  height: 32px; 			  border: 1px solid #ddd; 			  box-sizing: border-box; 		} 	 #canvas { 			  vertical-align: middle; 			  box-sizing: border-box; 			  border: 1px solid #ddd; 			  cursor: pointer; 	 } 	.btn { 			  display: block; 			  margin-top: 20px; 			  height: 32px; 			  width: 100px; 			  font-size: 16px; 			  color: #fff; 			  background-color: #457adb; 			  border: none; 			  border-radius: 50px; 	} 

js 部分

$(function(){   var show_num = [];   draw(show_num);   $("#canvas").on('click',function(){    draw(show_num);   })   $(".btn").on('click',function(){    var val = $(".input-val").val().toLowerCase();    var num = show_num.join("");    if(val==''){     alert('请输入验证码!');    }else if(val == num){     alert('提交成功!');     $(".input-val").val('');     // draw(show_num);    }else{     alert('验证码错误!请重新输入!');     $(".input-val").val('');     // draw(show_num);    }   })  })  //生成并渲染出验证码图形  function draw(show_num) {   var canvas_width=$('#canvas').width();   var canvas_height=$('#canvas').height();   var canvas = document.getElementById("canvas");//获取到canvas的对象,演员   var context = canvas.getContext("2d");//获取到canvas画图的环境,演员表演的舞台   canvas.width = canvas_width;   canvas.height = canvas_height;   var sCode = "a,b,c,d,e,f,g,h,i,j,k,m,n,p,q,r,s,t,u,v,w,x,y,z,A,B,C,E,F,G,H,J,K,L,M,N,P,Q,R,S,T,W,X,Y,Z,1,2,3,4,5,6,7,8,9,0";   var aCode = sCode.split(",");   var aLength = aCode.length;//获取到数组的长度   for (var i = 0; i < 4; i++) { //这里的for循环可以控制验证码位数(如果想显示6位数,4改成6即可)    var j = Math.floor(Math.random() * aLength);//获取到随机的索引值    // var deg = Math.random() * 30 * Math.PI / 180;//产生0~30之间的随机弧度    var deg = Math.random() - 0.5; //产生一个随机弧度    var txt = aCode[j];//得到随机的一个内容    show_num[i] = txt.toLowerCase();    var x = 10 + i * 20;//文字在canvas上的x坐标    var y = 20 + Math.random() * 8;//文字在canvas上的y坐标    context.font = "bold 23px 微软雅黑";    context.translate(x, y);    context.rotate(deg);    context.fillStyle = randomColor();    context.fillText(txt, 0, 0);    context.rotate(-deg);    context.translate(-x, -y);   }   for (var i = 0; i <= 5; i++) { //验证码上显示线条    context.strokeStyle = randomColor();    context.beginPath();    context.moveTo(Math.random() * canvas_width, Math.random() * canvas_height);    context.lineTo(Math.random() * canvas_width, Math.random() * canvas_height);    context.stroke();   }   for (var i = 0; i <= 30; i++) { //验证码上显示小点    context.strokeStyle = randomColor();    context.beginPath();    var x = Math.random() * canvas_width;    var y = Math.random() * canvas_height;    context.moveTo(x, y);    context.lineTo(x + 1, y + 1);    context.stroke();   }  }  //得到随机的颜色值  function randomColor() {   var r = Math.floor(Math.random() * 256);   var g = Math.floor(Math.random() * 256);   var b = Math.floor(Math.random() * 256);   return "rgb(" + r + "," + g + "," + b + ")";  }