JS实现根据密码长度 显示安全条详解编程语言

//根据密码长度显示安全条 
 
                    <ul class="clear"> 
                    <li>密　　码：</li> 
                    <li> <input type="password" id="pwd" name="pwd" class="in" onKeyUp=pwStrength(this.value) onBlur=pw_y("pwd","pwd1")></li> 
                    <li><em class="red">*</em></li> 
                    <li class="i2 grey"><table border="0" bordercolor="#cccccc" style='display:marker'> 
                    <tr align="center"> 
                        <td  id="strength_L"  bgcolor="#eeeeee">弱</td> 
                        <td  id="strength_M" bgcolor="#eeeeee">中</td> 
                        <td id="strength_H" bgcolor="#eeeeee">强</td> 
                    <td align="left" > 
                      <label id="pwd1">使用数字，字母，下划线，长度在 6 - 20 个字符之间</label></td> 
                        </tr> 
                    </table>                  
                    </li> 
                    </ul> 
 
function pwStrength(pwd){ 
    O_color="#eeeeee"; 
    L_color="#FF0000"; 
    M_color="#FF9900"; 
    H_color="#33CC00"; 
    if (pwd==null||pwd==''){ 
        Lcolor=Mcolor=Hcolor=O_color; 
    }else{ 
        S_level=checkStrong(pwd); 
        switch(S_level) { 
            case 0: 
                Lcolor=Mcolor=Hcolor=O_color; 
            case 1: 
                Lcolor=L_color; 
                Mcolor=Hcolor=O_color; 
                break; 
            case 2: 
                Lcolor=Mcolor=M_color; 
                Hcolor=O_color; 
                break; 
            default: 
                Lcolor=Mcolor=Hcolor=H_color; 
            } 
    } 
    document.getElementById("strength_L").style.background=Lcolor; 
    document.getElementById("strength_M").style.background=Mcolor; 
    document.getElementById("strength_H").style.background=Hcolor; 
    return; 
}