File file control, select a file (picture, flash, video) to preview and display immediately_form special effects

We usually use the file control to upload files. To preview, sometimes the page will be refreshed. As a result, the file control is cleared. Many people ask if they can not clear or reassign the value. This is impossible for security reasons. So how to preview without refreshing? Here I will write down the method I used.
Select page:

Copy code The code is as follows:

Display:

Copy code The code is as follows:

< ;div id="showimg">