J2EE study notes (2) Javascript discussion

In fact, Javascript is not strictly in the scope of J2EE, but because of its lightweight and fast and powerful client functions, we have to give Javascript three points.
Below are some of my limited javascript experience
1) javascript is mainly used to capture client events, validate data tables, and control page jump orientation. Each item has enough meaning to be mined. I will not mention it here.
2) in terms of verification, it is generally said that the server still needs to perform another test to ensure data consistency and effectiveness (to prevent the client from deliberately disabling the javascript check)
3) Javascript is very powerful, but not omnipotent. For example, in many cases, Javascript cannot be used to return to the previous page (history. back (), the main reason is to prevent repeated submission of forms. In this case, use Action to direct the initialization Action Method to the current page (a typical example is XXXAction. do? Method = initYYY