画布实现验证码

1，html部分

<canvas id="vCode" class="vCode" width="100" height="40"></canvas>

　

2,js部分

//生成验证码
            function createVCode() {
                var codeString = '0,1,2,3,4,5,6,7,8,9';
                codeString += ',A,B,C,D,E,F,G,H,I,J,K,L,M,N,O,P,Q,R,S,T,U,V,W,X,Y,Z';
                codeString += ',a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,t,z'
                var codeArr = codeString.split(',');
                var codeData = [];
                var codeLength = 0;
                while (codeLength < 4) {
                    codeLength = Math.ceil(Math.random() * 5);
                }
                for (var i = 0; i < codeLength; i++) {
                    codeData.push(codeArr[Math.ceil(Math.random() * 62) - 1]);
                }
                var StringCodeData = codeData.join('');
                return StringCodeData;
            }

　　

canvas渲染

function randomNum(min, max) {
                return Math.floor(Math.random() * (max - min) + min);
            }

            function randomColor(min, max) {
                var r = randomNum(min, max);
                var g = randomNum(min, max);
                var b = randomNum(min, max);
                return 'rgb(' + r + ',' + g + ',' + b + ')';
            }

            //显示验证码
            function renderCode(codeData) {
                console.log(codeData);
                var canvas = document.getElementById('vCode');
                var width = canvas.width;
                var height = canvas.height;
                var ctx = canvas.getContext('2d');
                ctx.fillStyle = randomColor(180, 240);
                ctx.fillRect(0, 0, width, height);
                ctx.textBaseline = 'bottom';
                for (var i = 0; i < codeData.length; i++) {
                    ctx.fillStyle = randomColor(30, 100);
                    ctx.font ='bold '+randomNum(22, 36) + 'px Arail';
                    var x = 10 + i * 16;
                    var y = randomNum(30, 40);
                    var deg = randomNum(-20, 20);
                    ctx.translate(x, y);
                    ctx.rotate(deg * Math.PI / 180);
                    ctx.fillText(codeData[i], 0, 0);
                    ctx.rotate(-deg * Math.PI / 180);
                    ctx.translate(-x, -y);
                }
                for (var j = 0; j < 5; j++) {
                    ctx.strokeStyle = randomColor(40, 180);
                    ctx.beginPath();
                    ctx.moveTo(randomNum(0, width), randomNum(0, height));
                    ctx.lineTo(randomNum(0, width), randomNum(0, height));
                    ctx.stroke();
                }
                for(var k =0;k<100;k++){
                    ctx.fillStyle = randomColor(0,255);
                    ctx.beginPath();
                    ctx.arc(randomNum(0,width),randomNum(0,height),1,0,2*Math.PI);
                    ctx.fill();
                }
            }