密码强度及输入合法性校验

密码规则：八位以及八位以上， 必须是数字，大小写字母，或者特殊字符四选三。

HTML代码：

  <div class="form-group">
                        <label class="col-sm-4 control-label is-required">登录密码：</label>
                        <div class="col-sm-8">
                            <input id = "password" name="password" placeholder="请输入登录密码" class="form-control" type="password"
                                   pattern='^(?=.*[A-Za-z])(?=.*[!@#$&*])(?=.*[0-9]).{8,}$' required>
                                <label style="color:green">密码强度</label>
                                <div style="position: absolute;width: 300px;border:solid 1px;height: 20px;background-color: red;">
                                <div style="position: absolute;width: 0;height: 20px;background-color: green;" id="green-bar"></div>
                                <span id="str" style="position: absolute;width: 100%;left:0;right: 0;text-align: center;color: white;font-weight: bold;">0%</span>
                                </div>
                        </div>
  </div>

js代码：

<script>
        var prefix = ctx + "system/user";

        document.getElementById("password").onkeyup = function(){
            var val = this.value;
            var strength = Math.round(password_strength(val));
            document.getElementById("green-bar").style.width = strength + "%";
            document.getElementById("str").innerText = strength + "%";
        };
        function password_strength(string){
            var h    = 0;
            var size = string.length;
            var result = {};
            string = ('' + string).split('').sort().join('').match(/(.)\1*/g);
            for (i = 0; i != string.length; i += 1) {
                result[string[i].charCodeAt(0)] = string[i].length;
            }
            for(var i in result){
                var p = result[i] / size;
                h -= p * Math.log(p) / Math.log(2);
            }
            var strength = (h / 4) * 100;
            if(strength > 100){
                strength = 100;
            }
            return strength;
        }
       //jQuery自定义校验validate
        jQuery.validator.addMethod("password", function(value, element) {
            //正则表达式
            var passWord = /^(?=.*[A-Za-z])(?=.*[!@#$&*])(?=.*[0-9]).{8,}$/;
            return this.optional(element) || (passWord.test(value));
        }, "请输入至少8位密码（至少包含1个字母，1个数字和1个特殊字符）");

       </script>

效果图：