本段代码摘取自jquery.form.js中，由于觉得该方法的使用性非常强，同时也可独立拿出来使用。
该段代码言简意赅可以很好的作为学习参考。
/**
* Clears the form data. Takes the following actions on the form's input fields:
* - input text fields will have their 'value' property set to the empty string
* - select elements will have their 'selectedIndex' property set to -1
* - checkbox and radio inputs will have their 'checked' property set to false
* - inputs of type submit, button, reset, and hidden will *not* be effected
* - button elements will *not* be effected
*/
$.fn.clearForm = function(includeHidden) {
return this.each(function() {
$('input,select,textarea', this).clearFields(includeHidden); //this表示设置上下文环境，有多个表单时只作用调用的表单
});
};
$.fn.clearFields = $.fn.clearInputs = function(includeHidden) {
var re = /^(?:color|date|datetime|email|month|number|password|range|search|tel|text|time|url|week)$/i; // 'hidden' is not in this list
return this.each(function() {
var t = this.type, tag = this.tagName.toLowerCase();
if (re.test(t) || tag == 'textarea') {
this.value = '';
}
else if (t == 'checkbox' || t == 'radio') {
this.checked = false;
}
else if (tag == 'select') {
this.selectedIndex = -1;
}
else if (t == "file") {
if (/MSIE/.test(navigator.userAgent)) {
$(this).replaceWith($(this).clone(true));
} else {
$(this).val('');
}
}
else if (includeHidden) {
// includeHidden can be the value true, or it can be a selector string
// indicating a special test; for example:
// $('#myForm').clearForm('.special:hidden')
// the above would clean hidden inputs that have the class of 'special'
if ( (includeHidden === true && /hidden/.test(t)) ||
(typeof includeHidden == 'string' && $(this).is(includeHidden)) ) {
this.value = '';
}
}
});
};