// JScript 文件
    function check_backa(){
    var title=document.getElementById("Demand_header1_TextBox1");
        if(title.value=="" || Alltrim(title.value)=="" )
        {
            alert("请输入关键字!");
            return false;
        }
        
    }
    function Alltrim(str) 
    { 
        while (str.charAt(0) == " " || str.charAt(0) == "　")
        {
            str = str.substr(1);
        }
        while (str.charAt(str.length - 1) == " " || str.charAt(0) == "　")
        {
            str = str.substr(0, str.length - 1);
        }
        return (str); 
    }