如何檢測是否沒有寫入表單（使用JavaScript）？

Question

這是我的javascript代碼：

if (username==null || isBlank(username)) 
    { 
    document.getElementById("warning").innerHTML="Please Fill Out Username Box".fontcolor("red"); 
    return false; 
    } 
if (email==null || isBlank(email)) 
    { 
    document.getElementById("warning").innerHTML="Please Fill Out Email Box".fontcolor("red"); 
    return false; 
    } 
    if (password==null || isBlank(password)) 
    { 
    document.getElementById("warning").innerHTML="Enter Password".fontcolor("red"); 
    return false; 
    } 

當我點擊提交按鈕和形式沒有點擊可言，打印什麼。問題是什麼？

Answer 1

這可能是你想要的？

<form action="" name="someform"> 
    <input type="text" name="inputname" /> 
    <input type="submit" value="submit" /> 
</form> 
<div id="warning"></div> 
<script type="text/javascript"> 
function testForm (e) { 
var inputname = this.inputname, 
    warning = false; 
    function isBlank (elem) { 
     return elem.value === ""; 
    } 
    // tests elems, you may put it into a loop 
    if (isBlank(inputname)){ 
     warning = "<span style=\"color:red;\">some warning</span>"; 
    } 
    // output 
    if (warning){ 
     e.preventDefault(); 
     document.getElementById("warning").innerHTML=warning; 
    } 
} 
// bind 
document.someform.onsubmit = testForm; 
</script>