JavaScript精简学习4（动态表单和链接处理）

JavaScript精简学习4：表单

43 表单构成
<form method=”post” action=”target.html” name=”thisForm”>
<input type=”text” name=”myText”>
<select name=”mySelect”>
<option value=”1”>First Choice</option>
<option value=”2”>Second Choice</option>
</select>
<br>
<input type=”submit” value=”Submit Me”>
</form>

44 访问表单中的文本框内容
<form name=”myForm”>
<input type=”text” name=”myText”>
</form>
<a href='http://www.webjx.com/htmldata/2006-02-06/1139212451.html#' onClick='window.alert(document.myForm.myText.value);'>Check Text Field</a>

45 动态复制文本框内容
<form name=”myForm”>
Enter some Text: <input type=”text” name=”myText”><br>
Copy Text: <input type=”text” name=”copyText”>
</form>
<a href=http://www.webjx.com/htmldata/2006-02-06/”#” onClick=”document.myForm.copyText.value =
document.myForm.myText.value;”>Copy Text Field</a>

46 侦测文本框的变化
<form name=”myForm”>
Enter some Text: <input type=”text” name=”myText” onChange=”alert(this.value);”>
</form>

47 访问选中的Select
<form name=”myForm”>
<select name=”mySelect”>
<option value=”First Choice”>1</option>
<option value=”Second Choice”>2</option>
<option value=”Third Choice”>3</option>
</select>
</form>
<a href='http://www.webjx.com/htmldata/2006-02-06/1139212451.html#' onClick='alert(document.myForm.mySelect.value);'>Check Selection List</a>

48 动态增加Select项
<form name=”myForm”>
<select name=”mySelect”>
<option value=”First Choice”>1</option>
<option value=”Second Choice”>2</option>
</select>
</form>
<script language=”JavaScript”>
document.myForm.mySelect.length++;
document.myForm.mySelect.options[document.myForm.mySelect.length - 1].text = “3”;
document.myForm.mySelect.options[document.myForm.mySelect.length - 1].value = “Third Choice”;
</script>

49 验证表单字段
<script language=”JavaScript”>
function checkField(field) {
if (field.value == “”) {
window.alert(“You must enter a value in the field”);
field.focus();
}
}
</script>
<form name=”myForm” action=”target.html”>
Text Field: <input type=”text” name=”myField”onBlur=”checkField(this)”>
<br><input type=”submit”>
</form>

50 验证Select项
function checkList(selection) {
if (selection.length == 0) {
window.alert(“You must make a selection from the list.”);
return false;
}
return true;
}

51 动态改变表单的action
<form name=”myForm” action=”login.html”>
Username: <input type=”text” name=”username”><br>
Password: <input type=”password” name=”password”><br>
<input type=”button” value=”Login” onClick=”this.form.submit();”>
<input type=”button” value=”Register” onClick=”this.form.action = ‘register.html’; this.form.submit();”>
<input type=”button” value=”Retrieve Password” onClick=”this.form.action = ‘password.html’; this.form.submit();”>
</form>

52 使用图像按钮
<form name=”myForm” action=”login.html”>
Username: <input type=”text” name=”username”><br>
Password: <input type=”password”name=”password”><br>
<input type=”image” src=http://www.webjx.com/htmldata/2006-02-06/”login.gif” value=”Login”>
</form>

53 表单数据的加密
<SCRIPT LANGUAGE='JavaScript'>
<!--
function encrypt(item) {
var newItem = '';
for (i=0; i < item.length; i++) {
newItem += item.charCodeAt(i) + '.';
}
return newItem;
}
function encryptForm(myForm) {
for (i=0; i < myForm.elements.length; i++) {
myForm.elements.value = encrypt(myForm.elements.value);
}
}

//-->
</SCRIPT>
<form name='myForm' onSubmit='encryptForm(this); window.alert(this.myField.value);'>
Enter Some Text: <input type=text name=myField><input type=submit>
</form>

上面的encryptForm方法把表单中的数据转换为编码，在提交表单之前完成了简单的表单数据加密～