Javascript authentication id method is fully implemented

var certCardValid = function(id){ 
        var arrVerifyCode = [1,0,"x",9,8,7,6,5,4,3,2]; 
        var wi = [7,9,10,5,8,4,2,1,6,3,7,9,10,5,8,4,2]; 
        var Checker = [1,9,8,7,6,5,4,3,2,1,1]; 
        var msg = ""; 
        if(id.length != 15 && id.length != 18) { 
            Ext.MessageBox.alert(" message "," Id number in common 15 or 18 position "); 
            return false; 
        } 

        var ai = id.length == 18 ?  id.substring(0,17) : id.slice(0,6) + "19" + id.slice(6,16); 

 
        if (!/^/d+$/.test(ai)) { 
            Ext.MessageBox.alert(" message "," Id card must be a number except the last one. "); 
            return false; 
        }  

 
        var yyyy = ai.slice(6,10); 
        var mm = ai.slice(10,12)-1;  
        var dd = ai.slice(12,14); 
        var d = new Date(yyyy,mm,dd); 
        var now = new Date(); 
        var year = d.getFullYear(); 
        var mon = d.getMonth();  
        var day = d.getDate(); 

 
        if (year != yyyy || mon != mm || day != dd) { 
            Ext.MessageBox.alert(" message "," Id card is invalid. "); 
            return false; 
        } 

 
        for(var i = 0,ret = 0; i < 17; i++){ 
            ret += ai.charAt(i) * wi[i]; 
        } 

        ai += arrVerifyCode[ret %= 11]; 
        ai = ai.toUpperCase(); 

 
        if(id.length == 18 && id != ai){ 
            Ext.MessageBox.alert(" message "," Id card is invalid. "); 
            return false; 
        } 
        return true; 
    };