Cách submit form HTML bằng JavaScript

Gọi hàm validate() trong sự kiện onsubmit của form. Nếu validate trả về true thì submit, false thì hủy.

Ví dụ

<html>
  <head>
    <title>Submit Form JavaScript</title>
    <script>
      function validate() {
        if (document.myForm.Name.value == "") { alert("Nhập tên!"); document.myForm.Name.focus(); return false; }
        if (document.myForm.EMail.value == "") { alert("Nhập Email!"); document.myForm.EMail.focus(); return false; }
        if (document.myForm.Zip.value == "" || isNaN(document.myForm.Zip.value) || document.myForm.Zip.value.length != 5) { alert("ZIP 5 số!"); document.myForm.Zip.focus(); return false; }
        if (document.myForm.Country.value == "-1") { alert("Chọn quốc gia!"); return false; }
        return true;
      }
    </script>
  </head>
  <body>
    <form action="/cgi-bin/test.cgi" name="myForm" onsubmit="return validate()">
      <table cellspacing="2" cellpadding="2" border="1">
        <tr><td align="right">Tên</td><td><input type="text" name="Name"/></td></tr>
        <tr><td align="right">Email</td><td><input type="text" name="EMail"/></td></tr>
        <tr><td align="right">Mã ZIP</td><td><input type="text" name="Zip"/></td></tr>
        <tr><td align="right">Quốc gia</td><td>
          <select name="Country">
            <option value="-1" selected>[Chọn]</option>
            <option value="1">Canada</option>
            <option value="2">Sri Lanka</option>
            <option value="3">Mexico</option>
          </select></td></tr>
        <tr><td align="right"></td><td><input type="submit" value="Gửi"/></td></tr>
      </table>
    </form>
  </body>
</html>