When you start firefox, the browser console opens. Console in Google Chrome and other Chromium-based browsers. Using a Timer and Saving State
|Modern browsers provide built-in development tools for JavaScript and other technologies. These tools include a console, which is similar to a shell interface, as well as tools for DOM inspection, debugging, and network activity analysis.
The console can be used to log information as part of the JavaScript development process. The console also allows you to interact with the web page by executing JavaScript expressions in the context of the page. Essentially, the console provides the ability to write JavaScript code and, if necessary, manage it.
This guide will teach you how to work with JavaScript console in your browser and introduce you to other built-in development tools you may find useful.
Working with the JavaScript Console in the Browser
Most modern web browsers that support HTML and XHTML provide by default access to a developer console, where you can work with JavaScript in a terminal shell-like interface. In this section, you will learn how to access the console in Firefox and Chrome.
Firefox browser
These tools allow you to inspect and edit DOM elements, as well as search HTML objects, Related specific page. The DOM can indicate whether a piece of text or an image has an ID attribute, and can determine the value of that attribute.
Additionally, in the sidebar or under the DOM panel you can find CSS styles, which are used in HTML document or style sheet.
To edit the DOM in real time, double-click on the selected element. For example, you can try turning the tag
V .
Again, after updating the page will take its previous appearance.
Network tab
The Network tab allows you to monitor and record network requests. This tab shows the browser's network requests, including requests to load the page, the time it took to service the requests, and information about each request. This data can be used to optimize page load performance and debug queries.
You can use the Network tab in conjunction with the JavaScript console. For example, you can start debugging a page using the console, and then open the Network tab and view network activity without reloading the page.
Responsive Design
Websites with responsive design quickly adapt their appearance and functionality to different devices: mobile phones, tablets, desktop computers and laptops. Screen size, pixel density, and touch response are factors to consider when designing responsive websites. It is also important to consider the principles of responsive design to ensure that the website is accessible and performant regardless of the device on which it is opened.
Modern browsers (including Firefox and Chrome) provide models for following responsive design principles when developing websites and applications. These models emulate the behavior of a particular device, which allows you to test and analyze all the functions of the site.
You can learn more about this in the browser manuals:
- Responsive Design Mode in Firefox
Conclusion
This guide presents short review working with the JavaScript console in modern web browsers. You can also find information about other useful development tools here.
Our website has already published many different Java scripts for social networks. And in the description of each script describe detailed instructions on their launch... This is of no use. We decided to write a full-fledged manual describing the installation of scripts on all browsers, and also take into account the presence of several installation methods on one specific browser and describe them all.
Running Java scripts through the browser console:
Now, as you know, launching scripts through the console is the most popular and simplest, and most importantly, working way to use them. Therefore, this is where we will start - with ways to get into the console for each browser.Console in Mozilla Firefox:
The easiest way to get to the web console in the Mozilla Firefox browser is by using a keyboard shortcut Ctrl + Shift + K. Click and the console will appear.Console in Google Chrome and other browsers based on Chromium:
In Google Chrome, Opera 15+, Amigo , Orbitum and other Chromium-based browsers also have a way to launch the web console using hotkeys. To do this, you need to simultaneously press Ctrl + Shift + J.
Console in Opera 12:
To launch the web console in the browser Opera of old generation (not older than version 12), you need to use the keyboard shortcut Ctrl + Shift + I. This will launch Opera Dragonfly, a toolbar for developers. After opening it, go to the tab Console.
Console in Internet Explorer:
To open the console in the Internet Explorer web browser, you must first click on the button F12, and then press the combination Ctrl + 2 (the two are on the central panel, not in the Num section).
Safari Console:
In Safari, before opening the console, you must enter the browser settings ( gear in the right top corner » Settings… » Add-ons) and enable the option Show Develop menu in menu bar. After this, the console can be called with a keyboard shortcut Ctrl + Alt + C.
All scripts are entered into the console in a specially designated field next to the arrow icon (see screenshots, areas for entering scripts are highlighted with a red frame). Scripts are launched by pressing a button Enter. After entering and running any script, you will see any comments or errors as they run.
Running Java scripts from the browser address bar:
The method of launching scripts from the browser's address bar is an older method, and rather even traditional. Initially, all scripts were launched this way. But trends change, the world develops. In most browsers, after pasting the script code into address bar you need to add code manually to run it, and in some browsers the address bar does not process java scripts at all.Address bar in Mozilla Firefox:
It's sad, but none of the most latest versions Mozilla browser Firefox does not support handling scripts through the address bar. Although more earlier versions a similar option was present in modern Firefox developers decided to give it up.Address bar in Google Chrome and other Chromium-based browsers:
IN Google browser Chrome and any other browser built on it source codes, such as Opera 15+, Amigo , Orbitum and others, you can run scripts in the address bar. But! After inserting the script, you must add the word before it javascript:(together with a colon), otherwise (thanks to such a phenomenon as omnibox) instead of running the script, a redirection to search engine.Address bar in Opera 12:
In the Opera 12 browser everything is much better. To run the script, just paste it into the address bar and run it. There shouldn't be any problems with this.Address bar in Internet Explorer:
IN this browser, as in Google Chrome and the like, after inserting the script into the address bar, at the very beginning you need to add javascript:(together with a colon), otherwise the script will not work.Address bar in Safari:
Well, in Safari things are just as good as in Opera 12. Just paste the existing script into the address bar and run it.Using browser plugins to store and run scripts:
If scripts need to be used constantly, then you need to tinker with them, copy them from the site or text file, paste into the address bar or console every time. Agree, this is not convenient. That is why special extensions (plugins) for browsers were invented, designed to store and run scripts. We will talk about two plugins: Greasemonkey for Mozilla Firefox and Tampermonkey for Google Chrome.Greasemonkey plugin for Mozilla Firefox:
The Greasemonkey plugin for Mozilla Firefox allows you to create, save and run scripts added by users. Be careful! When using scripts to delete or change something, immediately after adding them to the plugin they will be launched automatically. We strongly do not recommend adding scripts to the plugin, for example, to delete posts from the VKontakte wall when open page VKontakte (you never know).User manual: 
Tampermonkey plugin for Google Chrome:
The Tampermonkey plugin is an analogue of the Greasemonkey plugin for Firefox and in the same way allows you to create, save and run custom scripts. Be careful! When using scripts to delete or change something, immediately after adding them to the plugin they will be launched automatically. We strongly do not recommend adding scripts to the plugin, for example, to delete posts from the VKontakte wall when the VKontakte page is open (you never know).User manual: 
This is how the Greasemonkey and Tampermonkey plugins work. Everything is fast and simple. Added scripts do not disappear anywhere; they can also be turned on and off at any convenient time.
Conclusion:
All described methods for running Javascript are described for the latest versions of popular web browsers. If you are using another browser or more outdated version browser, and the methods for running scripts in it differ from those described in this article, please report this in the comments.The Mozilla browser provides many different tools to work with and to improve its performance. One of these improvements makes it possible to work with the console of the entire browser.
What is the console in the browser
This element is the same as the standard web console, but it allows you to work not with individual tabs, but with the search engine as a whole. That is, information about errors, requests and other actions is logged there.
The tool logs information not only of a separate tab, but also of add-ons, as well as the code of the search engine itself. To use other enhancements that are available in standard sets for web development, you should resort to using the Toolbar. The console is also used to execute various JavaScript expressions.
It is worth considering that starting from 30 this Firefox line is disabled. In order for the console to start in Mozilla, you need to assign the code true to the line about:config – devtools.chrome.enabled. You can also use another method to activate the improvement.
You must check the box next to “Enable Browser Chrome and add-ons debugging tools” for Firefox 40, in previous version The name of this column may vary slightly.
After opening the developer window, you can see that the interface is divided into 3 parts:
Features of working in web developer mode
In order to make the most of all the improvements, you need to know not only how to open the console, but also some secrets of working with it.
One of the very useful tools- console.log. It is used for debugging output, but advanced users also resort to several other methods of working with information. For example, the principle of operation of console.log is quite similar to printf.
Firefox also allows you to use the “%c” pattern to apply the second argument when formatting a style. Mozilla will display a small icon gray next to information, such as warnings or error messages. This means these notifications require attention. Debug messages are not indicated in this search engine, since, according to the developers, they are obsolete and console.log() should be used instead.
It is worth noting that in this search engine you can use several values at once. To do this, you need to separate them with commas, which is very convenient when included on one line.
Using a Timer and Saving State
Developer mode enabled means you can use a timer. It can be launched via console.time. Stopping the timer is done using console.timeEnd. Time is displayed in milliseconds.
The countdown begins from the moment the timer is activated. Additionally, you can create timestamps. They are used in conjunction with HTTP traffic timing to determine how long it took to execute a piece of code.
Quite often, information needs to be saved for reference or for tracking logs. You don't need to do anything to save the state or data displayed between page openings. Firefox will save this information automatically. You can even clear the message after activating the button in the upper right corner or by reopening the panel.
Opening the console in Mozilla Firefox is quite simple. To do this, you need to have basic skills that will help you control the operation of the browser and even improve it if necessary.
