javascript close console

JavaScript Close Console
If you are a front-end developer, you must often use the browser console (Console) to debug your code. The console can provide a lot of useful information, such as error messages, logs, performance analysis, etc.

However, in a production environment, it may be necessary to disable the console to protect your code and application. In addition, the console may leak information such as API keys, sensitive data, or cookies.

In this article, we will discuss how to close the console, how to prevent it from appearing, and some other practical suggestions.

1. Disabling the console using code

First, let’s see how to disable the console using code. Although the browser allows you to open the console, you can disable it with the following code:

// 如果控制台被打开则重定向
if (typeof console !== "undefined") {
  console.log("控制台被禁用");
  console.clear();
  window.location.href = "about:blank";
}

The above code monitors and disables the console from appearing. If the console is opened, it will be redirected to a blank page.

2. Disable F12

In addition to disabling the console, you can also disable F12. The F12 shortcut key is the default option for opening the console. In most cases, users will use this shortcut key to open the console.

In order to disable the shortcut key, you can add the following code to your HTML file:

<script>
    document.addEventListener("keydown", function(e) {
        // 禁用 F12
        if (e.keyCode === 123) {
            console.log("F12 键被禁用");
            e.preventDefault();
        }
    });
</script>

The above code listens for the F12 key and prevents the default behavior of this shortcut key.

3. Delete console logs before deploying the application to a production environment

If your application relies on Console log output, you should delete those unused Console statements , especially statements that print sensitive information to the console.

You can use the following code to delete the Console output statement:

// 删除 console.log()
if (!window.console) window.console = {};
if (!window.console.log) window.console.log = function() {};

// 删除 console.warn()
if (!window.console) window.console = {};
if (!window.console.warn) window.console.warn = function() {};

// 删除 console.error()
if (!window.console) window.console = {};
if (!window.console.error) window.console.error = function() {};

This will delete the Console log output, but you can still open the console by other means. Therefore, this solution is not perfect.

4. Prevent the console from being opened

You can also prevent the console from opening by modifying your JavaScript code. While this approach isn't perfect, it can work in some situations.

The following is a sample code to implement this method:

var oldLogs = [];

// 在页面加载时禁止控制台并覆盖 console.log()
(function() {
    var isChrome = !!window.chrome && (!!window.chrome.webstore || !!window.chrome.runtime);
    // 如果用户访问页面并且为 Chrome 浏览器，则禁用控制台
    if (isChrome) {
        setInterval(function() {
            // 如果控制台被打开，则刷新页面
            if((window.outerHeight - window.innerHeight) > 200){
                window.location.reload();
            }
        }, 1000);

        // 缓存先前的日志并覆盖 console.log()
        var oldLogs = [];
        if (!window.console) window.console = {};
        if (!window.console.log) window.console.log = function() {};
        if (!window.console.warn) window.console.warn = function() {};
        if (!window.console.error) window.console.error = function() {};
        window.console.log = function(log) {
            oldLogs.push(log);
        };
        window.console.warn = function(log) {
            oldLogs.push(log);
        };
        window.console.error = function(log) {
            oldLogs.push(log);
        };
    }
})();

The above code will detect whether the user uses the Chrome browser to access the page. If so, disable the console and prevent it from appearing. Additionally, it overwrites the Console's log output and stores the old logs in an array for later recall.

Although this method is relatively safe, it may fail to run on browsers such as Firefox or Safari.

Conclusion

Turning off the console is not a common practice in a production environment, but it is still sometimes necessary. Disabling the console protects your code and applications from attacks such as CSRF, XSS, DDoS, and more. However, we should be cautious about this and take other steps to protect our code and applications, such as using security suites and following best practices.

Finally, whether you disable the console or not, you can improve code quality and application performance by using it wisely.

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