HTMLFormElement

HTMLFormElement 介面提供了建立及修改 <form> 元素的方法。 document.forms - returns an array of HTMLFormElement objects referencing all forms on the page. document.forms[index] - returns an HTMLFormElement object referencing the form at the specified index. document.forms['id'] - returns an HTMLFormElement object referencing the form with the specified id. document.forms['name'] - returns an HTMLFormElement object referencing the form with the specified name.

屬性

This interface also inherits properties from its parent, HTMLElement.

HTMLFormElement.elements (en-US)Read only: A HTMLFormControlsCollection (en-US) holding all form controls belonging to this form element.
HTMLFormElement.length (en-US)Read only: A long reflecting the number of controls in the form.
HTMLFormElement.name (en-US): A DOMString reflecting the value of the form's name HTML attribute, containing the name of the form.
HTMLFormElement.method (en-US): A DOMString reflecting the value of the form's method HTML attribute, indicating the HTTP method used to submit the form. Only specified values can be set.
HTMLFormElement.target (en-US): A DOMString reflecting the value of the form's target HTML attribute, indicating where to display the results received from submitting the form.
HTMLFormElement.action (en-US): A DOMString reflecting the value of the form's action HTML attribute, containing the URI of a program that processes the information submitted by the form.
HTMLFormElement.encoding (en-US) or HTMLFormElement.enctype (en-US): A DOMString reflecting the value of the form's enctype HTML attribute, indicating the type of content that is used to transmit the form to the server. Only specified values can be set. The two methods are synonyms.
HTMLFormElement.acceptCharset (en-US): A DOMString reflecting the value of the form's accept-charset HTML attribute, representing the character encoding that the server accepts.
HTMLFormElement.autocomplete: A DOMString reflecting the value of the form's autocomplete HTML attribute, indicating whether the controls in this form can have their values automatically populated by the browser.
HTMLFormElement.noValidate: A Boolean reflecting the value of the form's novalidate HTML attribute, indicating whether the form should not be validated.

方法

This interface also inherits methods from its parent, HTMLElement.

HTMLFormElement.submit() (en-US): Submits the form to the server.
HTMLFormElement.reset() (en-US): Resets the form to its initial state.
HTMLFormElement.checkValidity(): Returns true if the element's child controls are subject to constraint validation and satisfy those contraints; returns false if some controls do not satisfy their constraints. Fires an event named invalid (en-US) at any control that does not satisfy its constraints; such controls are considered invalid if the event is not canceled. It is up to the programmer to decide how to respond to false.
HTMLFormElement.reportValidity() (en-US): Returns true if the element's child controls satisfy their validation constraints. When false is returned, cancelable invalid (en-US) events are fired for each invalid child and validation problems are reported to the user.
HTMLFormElement.requestAutocomplete(): Triggers a native browser interface to assist the user in completing the fields which have an autofill field name value that is not off or on. The form will receive an event once the user has finished with the interface, the event will either be autocomplete when the fields have been filled or autocompleteerror when there was a problem.

範例

Create a new form element, modify its attributes and submit it:

var f = document.createElement("form"); // Create a form
document.body.appendChild(f); // Add it to the document body
f.action = "/cgi-bin/some.cgi"; // Add action and method attributes
f.method = "POST";
f.submit(); // Call the form's submit method

Extract information from a form element and set some of its attributes:

<form name="formA" id="formA" action="/cgi-bin/test" method="POST">
  <p>Click "Info" for form details; "Set" to change settings.</p>
  <p>
    <input type="button" value="info" onclick="getFormInfo();" />
    <input type="button" value="set" onclick="setFormInfo(this.form);" />
    <input type="reset" value="reset" /><br />
    <textarea id="tex" style="height:15em; width:20em"></textarea>
  </p>
</form>

<script type="text/javascript">
  function getFormInfo() {
    var info;
    var f = document.forms["formA"]; //Get a reference to the form via id.
    info =
      "elements: " +
      f.elements +
      "\n" +
      "length: " +
      f.length +
      "\n" +
      "name: " +
      f.name +
      "\n" +
      "charset: " +
      f.acceptCharset +
      "\n" +
      "action: " +
      f.action +
      "\n" +
      "enctype: " +
      f.enctype +
      "\n" +
      "encoding: " +
      f.encoding +
      "\n" +
      "method: " +
      f.method +
      "\n" +
      "target: " +
      f.target;
    document.forms["formA"].elements["tex"].value = info;
  }
  function setFormInfo(f) {
    //Argument is a reference to the form.
    f.method = "GET";
    f.action = "/cgi-bin/evil_executable.cgi";
    f.name = "totally_new";
  }
</script>

Submit a form in a popup window (en-US):

<!DOCTYPE html>
<html>
  <head>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
    <title>MDN Example</title>
    <script type="text/javascript">
      function popupSend(oFormElement) {
        if (
          oFormElement.method &&
          oFormElement.method.toLowerCase() !== "get"
        ) {
          console.error("This script supports the GET method only.");
          return;
        }
        var oField,
          sFieldType,
          nFile,
          sSearch = "";
        for (var nItem = 0; nItem < oFormElement.elements.length; nItem++) {
          oField = oFormElement.elements[nItem];
          if (!oField.hasAttribute("name")) {
            continue;
          }
          sFieldType =
            oField.nodeName.toUpperCase() === "INPUT"
              ? oField.getAttribute("type").toUpperCase()
              : "TEXT";
          if (sFieldType === "FILE") {
            for (
              nFile = 0;
              nFile < oField.files.length;
              sSearch +=
                "&" +
                escape(oField.name) +
                "=" +
                escape(oField.files[nFile++].name)
            );
          } else if (
            (sFieldType !== "RADIO" && sFieldType !== "CHECKBOX") ||
            oField.checked
          ) {
            sSearch += "&" + escape(oField.name) + "=" + escape(oField.value);
          }
        }
        open(
          oFormElement.action.replace(/(?:\?.*)?$/, sSearch.replace(/^&/, "?")),
          "submit-" + (oFormElement.name || Math.floor(Math.random() * 1e6)),
          "resizable=yes,scrollbars=yes,status=yes"
        );
      }
    </script>
  </head>

  <body>
    <form
      name="yourForm"
      action="test.php"
      method="get"
      onsubmit="popupSend(this); return false;">
      <p>
        First name: <input type="text" name="firstname" /><br />
        Last name: <input type="text" name="lastname" /><br />
        Password: <input type="password" name="pwd" /><br />
        <input type="radio" name="sex" value="male" /> Male
        <input type="radio" name="sex" value="female" /> Female
      </p>
      <p>
        <input type="checkbox" name="vehicle" value="Bike" />I have a bike<br />
        <input type="checkbox" name="vehicle" value="Car" />I have a car
      </p>
      <p><input type="submit" value="Submit" /></p>
    </form>
  </body>
</html>