正则验证密码

function myfunction(){
    var x = document.getElementById("input1");
    c =  /^[a-zA-Z0-9]{6,8}$/;				
    if((x.value).match(c)){
        alert("输入正确！");
        w.style.display="none";
    }
    else if((x.value)==""){
        alert("请输入！");
    }
    else{
        alert("错误！");
        x.value = "";
    }
}