本文实例为大家分享了js生成图形验证码的具体代码，供大家参考，具体内容如下

getGVerify:function (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
        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");
        /*this.options.width = con.offsetWidth > 0 ? con.offsetWidth : "100";
        this.options.height = con.offsetHeight > 0 ? con.offsetHeight : "30";*/
        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 <= 4; i++) {
          var txt = txtArr[randomNum(0, txtArr.length)];
          this.options.code += txt;
          ctx.font = '20px 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.shadowOffsetX = randomNum(-3, 3);
          ctx.shadowOffsetY = randomNum(-3, 3);*/
          ctx.shadowBlur = randomNum(-3, 3);
          ctx.shadowColor = "rgba(0, 0, 0, 0.3)";
          var x = this.options.width / 5 * 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);
  }

调用方法

var verifyCode = new GVerify(id);

验证方法

if(verifyCode.validate(inputCode)){
   return true;
}esle{
   return false;
}

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持自学php网。