Specific implementation of disabling some JavaScript methods on the page_javascript skills

The method discussed in this article has not been applied in actual projects because I have not encountered a project with such a need, but the experiment found that it is feasible.

1. Source of my ideas

JavaScipt is a good thing. Its appearance makes the web page expression more lively. Of course, the benefits are not just these, but the recent The booming AJAX applications in recent years have made people pay more attention to the application of JavaScript small language (many programmers do not regard it as a language, at most it is called a script, and even look down on people who engage in scripting). Nowadays, many blog official websites open script permissions, allowing users to customize scripts to enrich their own space. Especially some technical and professional blogs provide a fairly relaxed development environment. But we also found that many blogs will restrict certain script methods. Note that what I am talking about here is partial restriction. If it is full restriction, it is very simple. Just filter out the <script> script block. But how is partial restriction achieved? <br><br>Because I have not encountered such a problem in previous projects, I did not do too much in-depth research. At first, I just thought of using the "replacement" method based on my feeling. Obviously such an approach won't work because something could go wrong. For example, if I want to disable the alert method, I have the following code: <BR><div class="codetitle"><span><a style="CURSOR: pointer" data="67741" class="copybut" id="copybut67741" onclick="doCopy('code67741')"><U>Copy the code The code is as follows: <div class="codebody" id="code67741"> <BR>window.alert('Some message'); <BR> <BR>Now to make the above code invalid, just change the alert. For example, change it all to uppercase ALERT, which is sure A script error will be reported, but you can still use try{}catch{} to include ALERT, but this is a big problem for the identification of disabled language packages, and there will also be such errors: document.write('alert The alert in some message'); has also been replaced. <br><br>Later I thought of method rewriting, rewriting the method to be disabled and making it do nothing. It turned out to be really feasible, but I didn’t know if it was a scientific method. I came up with Let’s discuss it together. <br><br><STRONG>2. Specific implementation <br><br>First look at the following code to disable the "alert" and "write" methods: <BR><div class="codetitle"> <span><a style="CURSOR: pointer" data="59455" class="copybut" id="copybut59455" onclick="doCopy('code59455')"><U>Copy code The code is as follows:<div class="codebody" id="code59455"> <BR>window.alert=function(){} <BR>document.write=function( ){} <br><br>window.alert('Alert some message'); <BR>document.write('Write some message'); <BR> <BR>Looks really simple, In actual application, extract the first two lines separately and store them in an external JS file, and load this JS file first on the page that needs to filter the JavaScript method (you can also load this script on the line before the user edits the content block, so that before In the HTML block, our administrators or web page creators can still use the method that will be disabled), so calling the disabled method later will not work. <br><br><STRONG>Note: Finally, please disable some DOM operation methods, such as the remove() method, because users can use DOM operation methods to remove the JS file you loaded at the beginning. .</script>