前端小功能：canvas验证码

function getGVerify(id){
  
    function GVerify(options) { //创建一个图形验证码对象，接收options对象为参数
        this.options = { //默认options参数值
            id: "", //容器Id
            canvasId: "verifyCanvas", //canvas的ID
            width: "100", //默认canvas宽度
            height: "30", //默认canvas高度
            fontSize: "20", //默认字体大小
            numSize: 4 , //默认验证码个数 类型为number
            type: "blend", //图形验证码默认类型blend:数字字母混合类型、number:纯数字、letter:纯字母
            code: ""
        }

        if(Object.prototype.toString.call(options) == "[object Object]"){//判断传入参数类型
        for(var i in options) { //根据传入的参数，修改默认参数值
            this.options[i] = options[i];
        }
        }else{
            this.options.id = options;
        }

        this.options.numArr = "0,1,2,3,4,5,6,7,8,9".split(",");
        this.options.letterArr = getAllLetter();

        this._init();
        this.refresh();
    }
  
    GVerify.prototype = {
        /**版本号**/
        version: ‘1.0.0‘,
      
        /**初始化方法**/
        _init: function() {
            var con = document.getElementById(this.options.id);
            var canvas = document.createElement("canvas");
            canvas.id = this.options.canvasId;
            canvas.width = this.options.width;
            canvas.height = this.options.height;
            canvas.style.cursor = "pointer";
            canvas.innerHTML = "您的浏览器版本不支持canvas";
            con.appendChild(canvas);
            var parent = this;
            canvas.onclick = function(){
              parent.refresh();
            }
         },
      
          /**生成验证码**/
        refresh: function() {
            this.options.code = ‘‘;
            var canvas = document.getElementById(this.options.canvasId);
            if(canvas.getContext) {
              var ctx = canvas.getContext(‘2d‘);
            }
            ctx.textBaseline = "middle";
      
            ctx.fillStyle = randomColor(180, 240);
            ctx.fillRect(0, 0, this.options.width, this.options.height);
      
            if(this.options.type == "blend") { //判断验证码类型
              var txtArr = this.options.numArr.concat(this.options.letterArr);
            } else if(this.options.type == "number") {
              var txtArr = this.options.numArr;
            } else {
              var txtArr = this.options.letterArr;
            }
      
            for(var i = 1; i <= this.options.numSize; i++) {
              var txt = txtArr[randomNum(0, txtArr.length)];
              this.options.code += txt;
              ctx.font = this.options.fontSize + ‘px SimHei‘;
              //ctx.font = randomNum(this.options.height/2, this.options.height) + ‘px SimHei‘; //随机生成字体大小
              ctx.fillStyle = randomColor(50, 160); //随机生成字体颜色
              ctx.shadowBlur = randomNum(-3, 3);
              ctx.shadowColor = "rgba(0, 0, 0, 0.3)";
              var x = this.options.width / (this.options.numSize + 1) * i;
              var y = this.options.height / 2;
              var deg = randomNum(-30, 30);
              /**设置旋转角度和坐标原点**/
              ctx.translate(x, y);
              ctx.rotate(deg * Math.PI / 180);
              ctx.fillText(txt, 0, 0);
              /**恢复旋转角度和坐标原点**/
              ctx.rotate(-deg * Math.PI / 180);
              ctx.translate(-x, -y);
            }
            /**绘制干扰线**/
            for(var i = 0; i < 4; i++) {
              ctx.strokeStyle = randomColor(40, 180);
              ctx.beginPath();
              ctx.moveTo(randomNum(0, this.options.width/2), randomNum(0, this.options.height/2));
              ctx.lineTo(randomNum(0, this.options.width/2), randomNum(0, this.options.height));
              ctx.stroke();
            }
            /**绘制干扰点**/
            for(var i = 0; i < this.options.width/4; i++) {
              ctx.fillStyle = randomColor(0, 255);
              ctx.beginPath();
              ctx.arc(randomNum(0, this.options.width), randomNum(0, this.options.height), 1, 0, 2 * Math.PI);
              ctx.fill();
            }
        },
      
          /**验证验证码**/
        validate: function(code){
            var verifyCode = code.toLowerCase();
            var v_code = this.options.code.toLowerCase();
            if(verifyCode == v_code){
              return true;
            }else{
              return false;
            }
        }
    }
  
    /**生成字母数组**/
    function getAllLetter() {
      var letterStr = "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,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";
      return letterStr.split(",");
    }
    /**生成一个随机数**/
    function randomNum(min, max) {
      return Math.floor(Math.random() * (max - min) + min);
    }
    /**生成一个随机色**/
    function randomColor(min, max) {
      var r = randomNum(min, max);
      var g = randomNum(min, max);
      var b = randomNum(min, max);
      return "rgb(" + r + "," + g + "," + b + ")";
    }
  
    return new GVerify(id);
}

var getGVerify = getGVerify({
    id: ‘validate‘,
    width: ‘200‘,
    height: ‘60‘,
    fontSize: ‘40‘,
    numSize: 4,
    type: ‘blend‘
});
var flag = getGVerify.validate(‘13dd‘)

!(function(window, document) {
     ......
     window.GVerify = GVerify;
})(window, document);        

var verifyCode = new GVerify("v_container");
var res = verifyCode.validate(value);