如何将表单的内容发布到它所在的页面？

In Yahoo or Google and in many websites when you fill up a form and if your form has any errors it gets redirected to the same page. Note that the data in the form remains as it is. I mean the data in the text fields remains the same. I tried ‹form action="(same page here)" method="post or get"›. It gets redirected to the page, but the contents of the form gets cleared. I want the data to be displayed.In Yahoo or Google and in many websites when yo