錯誤檢查對「假」

Question

我用這個JavaScript語法用於驗證複選框...

alert(document.getElementById("ctl00_ContentPlaceHolder1_Chkreg").checked); 
    if (document.getElementById("ctl00_ContentPlaceHolder1_Chkreg").checked == false) { 
     document.getElementById("ctl00_ContentPlaceHolder1_ErrorMsg").innerHTML = "please select the checkbox"; 
     document.getElementById("ctl00_ContentPlaceHolder1_Chkreg").focus(); 
     return false; 
    } 

我的警報給我假，但我如果循環不工作...任何建議...

屬性

Answer 1

假設未選中你的盒子，我會親自寫，如：

var box = document.getElementById("ctl00_ContentPlaceHolder1_Chkreg"); 
if (!box.checked) { 
    document.getElementById("ctl00_ContentPlaceHolder1_ErrorMsg").innerHTML = "please select the checkbox"; 
    box.focus(); 
    return false; 
}