原始碼：

!(function(window, document) {
    function GVerify(options) { //建立一個圖形驗證碼物件，接收options物件為引數
    this.options = { //預設options引數值
         id: "", //容器Id
         canvasId: "verifyCanvas", //canvas的ID
         width: "100", //預設canvas寬度
         height: "30", //預設canvas高度
         type: "blend", //圖形驗證碼預設型別blend:數字字母混合型別number:純數字、letter:純字母
         code: ""
    }

if(Object.prototype.toString.call(options) == "[object Object]"){
//判斷傳入引數型別
   for(var i in options) { //根據傳入的引數，修改預設引數值
      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 = {
/**版本號**/
   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 = "您的瀏覽器版本不支援canvas";
   con.appendChild(canvas);
   var parent = this;
   canvas.onclick = function(){
      parent.refresh();
   }
},

/**生成驗證碼**/
refresh: function() {
   this.options.code = "";
   var canvas = document.getElementById(this.options.canvasId);
   if(canvas.getContext) {
      var ctx = canvas.getContext('2d');
   }else{
      return;
   }

   ctx.textBaseline = "middle";

   ctx.fillStyle = randomColor(180, 240);
   ctx.fillRect(0, 0, this.options.width, this.options.height);

   if(this.options.type == "blend") { //判斷驗證碼型別
       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 = randomNum(this.options.height/2, this.options.height) + 'px SimHei'; //隨機生成字型大小
      ctx.fillStyle = randomColor(50, 160); //隨機生成字型顏色 
      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);
      /**設定旋轉角度和座標原點**/
      ctx.translate(x, y);
      ctx.rotate(deg * Math.PI / 180);
      ctx.fillText(txt, 0, 0);
      /**恢復旋轉角度和座標原點**/
      ctx.rotate(-deg * Math.PI / 180);
      ctx.translate(-x, -y);
}
/**繪製干擾線**/
  for(var i = 0; i < 4; i++) {
     ctx.strokeStyle = randomColor(40, 180);
     ctx.beginPath();
     ctx.moveTo(randomNum(0, this.options.width), randomNum(0,           this.options.height));
     ctx.lineTo(randomNum(0, this.options.width), randomNum(0, this.options.height));
     ctx.stroke();
}
/**繪製干擾點**/
  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();
  }
},

/**驗證驗證碼**/
   validate: function(code){
   var code = code.toLowerCase();
   var v_code = this.options.code.toLowerCase();
   console.log(v_code);
   if(code == v_code){
     return true;
   }else{
     this.refresh();
     return false;
   }
  }
}
/**生成字母陣列**/
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(",");
}
/**生成一個隨機數**/
function randomNum(min, max) {
   return Math.floor(Math.random() * (max - min) + min);
}
/**生成一個隨機色**/
function randomColor(min, max) {
   var r = randomNum(min, max);
   var g = randomNum(min, max);
   var b = randomNum(min, max);
   return "rgb(" + r + "," + g + "," + b + ")";
}
window.GVerify = GVerify;
})(window, document);
 

使用方法

html

<div id="v_container" style="width: 200px;height: 50px;"></div>
<input type="text" id="code_input" value="" placeholder="請輸入驗證碼"/><button id="my_button">驗證</button>

script

<script src="js/gVerify.js"></script>//引入外掛
//呼叫
<script>
    var verifyCode = new GVerify("v_container");
    document.getElementById("my_button").onclick = function(){
    var res =   verifyCode.validate(document.getElementById("code_input").value);
    if(res){
       alert("驗證正確");
    }else{
       alert("驗證碼錯誤");
    }
}
</script>