As browser security improves, it becomes increasingly difficult to preview images. However, the wisdom of the crowd is unlimited, and there are many alternative or advanced methods to achieve it online. After studying various preview methods, as a summary, I wrote this program to share with you. The simple non-refresh file upload system I wrote last time was originally designed to achieve this image preview effect. Compatible with: ie6/7/8, firefox 3.5.5 Also compatible with background support: opera 10.10, safari 4.0.4, chrome 3.0