javascript检查表单数据是否改变
有的时候,需要检查用户是否修改了一个表单中的内容,则可以使用下面的技巧,其中如果修改了表单的内容则返回true,没修改表单的内容则返回false。代码如下:
- function formIsDirty(form) {
- for (var i = 0; i < form.elements.length; i++) {
- var element = form.elements[i];
- var type = element.type;
- if (type == "checkbox" || type == "radio") {
- if (element.checked != element.defaultChecked) {
- return true;
- }
- }
- else if (type == "hidden" || type == "password" || type == "text" || type == "textarea") {
- if (element.value != element.defaultValue) {
- return true;
- }
- }
- else if (type == "select-one" || type == "select-multiple") {
- for (var j = 0; j < element.options.length; j++) {
- if (element.options[j].selected != element.options[j].defaultSelected) {
- return true;
- }
- }
- }
- }
- return false;
- }
- window.onbeforeunload = function(e) {
- e = e || window.event;
- if (formIsDirty(document.forms["someForm"])) {
- if (e) {
- e.returnValue = "You have unsaved changes.";
- }
- return "You have unsaved changes.";
- }
- };