function GetNull(x,y) //x为文本框的id，y为文本框的默认value，作用点击文本框时清空指定内容
{
	var obj = document.getElementById(x);
	if(obj.value == y)
	{
		obj.value = '';
		
	}
	
}

function trim(str) //全角、半角空格判断
{
        str = str.replace(/\　*/g, "");
		var i = 0;
        var len = str.length;
        if ( str == "" ) return( str );
        j = len -1;
        flagbegin = true;
        flagend = true;
        while ( flagbegin == true && i< len)
        {
           if ( str.charAt(i) == " " )
                {
                  i=i+1;
                  flagbegin=true;
                }
                else
                {
                        flagbegin=false;
                }
        }
        while  (flagend== true && j>=0)
        {
            if (str.charAt(j)==" ")
                {
                        j=j-1;
                        flagend=true;
                }
                else
                {
                        flagend=false;
                }
        }
        if ( i > j ) return ("")
        trimstr = str.substring(i,j+1);
        return trimstr;
}


function validate(x,y,z) //x为文本框的id，y为文本框的默认value，z为弹出的提示框内容，作用是判断关键字是否为空
{
		var obj = document.getElementById(x);
		if(obj.value==y){
			obj.value='';
			}
		if (trim(obj.value)=='') {
                window.alert (z);
				obj.focus();
                return false;
        }	
       // return true;

}


//以下为判断email地址是否输入正确,用时需调用js/string.js
function mailcheck(madd){
	var regu = "^(([0-9a-zA-Z]+)|([0-9a-zA-Z]+[_.0-9a-zA-Z-]*[0-9a-zA-Z]+))@([a-zA-Z0-9-]+[.])+([a-zA-Z]{2}|net|NET|com|COM|gov|GOV|mil|MIL|org|ORG|edu|EDU|int|INT)$"
	var re = new RegExp(regu);
	if (madd.search(re) != -1) {
		return true;  //地址正确
	} else {
		return false;//地址错误
	}
}

function chkemail(x,y,z) { //x为文本框的id，y为提示文字“输入email”，z为提示文字“email格式不对”，作用是判断是否输入正确email
	    error = false;
		msg = "Error\n";
	
		if(document.getElementById(x).value.trim()=='') {
			msg = msg +y+"\n";
			error = true;
		}else{
			if(!mailcheck(document.getElementById(x).value.trim()))
			{
				msg = msg +z+"\n";
				error = true;
			}
		}
		
		if(error){
			window.alert(msg);	
			return false;
		}
		
        return true

}