This article will teach you how to copy and paste online class assignments. It has certain reference value. Friends in need can refer to it. I hope it will be helpful to everyone.

#I woke up in the morning and opened my eyes. Oh, exam week is here again. Midterm assignments for each subject have been released on their respective platforms. All kinds of messy subjects are annoying.

Taking the iwrite English teaching platform as an example, let’s first make up for the English composition that I missed before. As soon as I clicked on the input box, a message box popping up prohibiting pasting, emmm, this is college, don't we even have this basic trust between teachers and students?

However, as a quasi-programmer, this problem is not difficult for me. The essence of programming is to process information. The meaning of programming is to improve efficiency. The joy of programming lies in solving problems. Since you encountered this problem today, pour a cup of tea and slowly solve this bug

Why can't I paste?

First of all, we need to understand the content copied by ctrl c. Why can't we paste it through ctrl v? Through the study of front-end knowledge, I know that the message pop-up box and mouse behavior on the web page are all controlled by javascript. Then prohibiting pasting on the web page actually means that the web page prohibits the paste behavior of the right mouse button.

After checking the information, I found that this is indeed the case. The following are the statements in JavaScript that turn on or off specific functions of the web page. Obviously, in the Js files of platforms like iwrite , the paste function has been false processed. If you also want to add disgusting functions like this to your webpage during website development, just enter the following code into your Js code.

script type=text/javascript// 禁止右键菜单
document.oncontextmenu = function(){ 
    return false; 
};// 禁止文字选择
document.onselectstart = function(){ 
    return false;
};// 禁止复制
document.oncopy = function(){
    return false;
};// 禁止剪切
document.oncut = function(){ 
    return false; 
};// 禁止粘贴
document.onpaste = function(){ 
    return false; 
};/script

From a technical perspective, just find the document.onpaste = function(){ return false; }; statement directly on the front-end page and change its return value to true. However, More web pages implement dynamic Js events for the mouse. This idea is first eliminated by Pass, so you can only skip the statement that disables pasting by disabling JavaScript.

Now that we know that the reason is because JavaScript restricts the paste function, the idea of ​​​​solving the bug is very clear. As long as the browser disables JavaScript, the problem will be solved. Solved easily.

Wait a minute, is the problem really just as simple as disabling JavaScript? In fact, this is indeed the case. Disabling JavaScript is equivalent to turning off front-end verification. There is a saying in the programming world: Front-end verification prevents gentlemen, and back-end verification prevents villains. What it means is that the security of front-end verification is 0, while the security of back-end verification is impregnable.

Front-end verification is generally to increase user experience, but the experience of prohibiting pasting is very subtle, which is very annoying; and important verification, such as login user name, password and other important information , all have to be handed over to the backend for verification through backend technology, such as JSR303, etc. The former reduces the pressure on the server, and the latter is more secure. The combination of the two is wonderful.

For example: Suppose there is a simple user login function, and we only do front-end testing. Then at this time, the user can press the F12 key to manually modify the front-end code through the browser console, manually change the front-end verification rules or directly close it. At this time, even if the wrong password is entered, the You can log in successfully. The reason is the lack of more secure backend verification.

Fortunately, the function of disabling paste is controlled by JavaScript, which only involves front-end content. The following method solves this problem by disabling JavaScript

Solution

First of all, Press F12 on the page where you want to paste, open the console

, and then press F1 on the console page Key to open the console settings

Find and check the Disable JavaScript checkbox in Debugger on the console settings page.

At this time, the JavaScript function has been disabled, and the paste function of the page has been restored. Quickly paste your own composition.

After submission, I successfully got a score of 81 points, so I guess the timing function of the page is not within the scope of machine scoring, and you can use it with confidence.

The above solution is actually applicable to situations where content on some websites cannot be copied. For example, in a certain library, you need to pay to copy text. By disabling JavaScript, you can also copy large sections of text. By solving this small learning problem, you can see that both the front-end and the back-end are actually very interesting!

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