What is console.log

The console. Syntax: Hey geek! The constant emerging technologies in the world of web development always keeps the excitement for this subject through the roof. But before you tackle the big projects, we suggest you start by learning the basics. Now at it's lowest price ever!

Return value: It returns the value of the parameter given. JavaScript codes to show the working of this function: 1 Passing a number as an argument: If the number is passed to the function console. Code Skip to content. Change Language. This checks to see if the console is present, and if not it sets it to an object with a blank function called log.

This way window. You can view any messages logged to the console if you use a tool such as Firebug to inspect your code. Let's say you do this:. When you access the console in Firebug or whichever tool you decide to use to inspect your code , you will see whatever message you told the function to log.

It's actually rather valuable for figuring out just what went wrong with your code. It will post a log message to the browser's javascript console, e.

You can use various methods, but beware that for it to work in Firefox, you must have Firebug open, otherwise the whole page will crash. Whether what you're logging is a variable, array, object or DOM element, it will give you a full breakdown including the prototype for the object as well always interesting to have a poke around. You can also include as many arguments as you want, and they will be replaced by spaces. You can also use console. And then end it with console.

Traces, groups, profiling, object inspection. As suggested in the comment, you can also execute that in one place and then use console.

On Firefox it is a very powerful tool, allowing you to inspect objects or examine the layout or other properties of HTML elements. It isn't related to jQuery, but there are two things that are commonly done when using it with jQuery:. This, amongst other advantages, makes the logging of jQuery objects look nicer. A point of confusion sometimes is that to log a text message along with the contents of one of your objects using console.

This in most cases is not explicitly overriden and the default implementation inherited by Object doesn't provide any useful information. Many people use alert hasNinjas for this purpose but console.

Using an alert pop-ups up a modal dialog box that blocks the user interface. An example - suppose you want to know which line of code you were able to run your program before it broke! Beware: leaving calls to console in your production code will cause your site to break in Internet Explorer. Never keep it unwrapped. In early days JS debugging was performed through alert function - now it is an obsolete practice.

The console. In a browser you will not see anything on the screen. It logs a message to a debugging console. It does not work well in all IE releases. If your browser supports debugging, you can use the console. Activate debugging in your browser with F12 , and select "Console" in the debugger menu. Console in JavaScript. Try to fix, or "debug," a non-functioning JavaScript program, and practice using the console. There are shortcuts that is going to help you to access to the JavaScript console, based on the browser that you are using:.

It can be used to alert you that there's an issue, but shouldn't take the place of an interactive debugger when it comes time to debug the code. Its asynchronous nature means that the logged values don't necessarily represent the value when the method was called. In short: log errors with console.

It is specially used for debugging. It is used to log anything you pass it to the Firebug console. The main usage would be to debug your JavaScript code. Apart from the usages mentioned above, console.

A server created with express for eg. This is nothing to deal with the jQuery. These methods are intended for debugging purposes only and should not be relied on for presenting information to end users. In java scripts there is no input and output functions.

So to debug the code console. It is a method for logging. It will be printed under console log development tools. Quoting MDN Docs here. By far the most commonly-used method is console. Using the alert method isn't bad. It works fine for simple situations, but as your code starts to do more, relying on them doesn't work as well. For starters, you'll probably go insane from dismissing the large number of dialogs that keep popping up while your code is running! You'll also want an easy way to persist the messages you are seeing.

The fleeting nature of of our alert dialogs makes any sort of long-term logging like that difficult. In this tutorial, we're going to look at one of the greatest inventions of all time that makes it easy to help us figure out what our code is doing. We are going to be learning about something known as the console. To kick your JavaScript skills into outer space, everything you see here and more with all its casual clarity!

Even if you think you write the most perfect JavaScript, you'll be spending a fair amount of time in what is known as the console. If you've never used the console before, it is part of your browser's developer tools where all sorts of text and stuff gets printed for you to see and occasionally interact with.

In this article, we won't focus on all of the things your console is capable of doing. Instead, we're just going to take it easy and gradually get you comfortable with using the console to just display messages. We will cover all of the crazy console-related things eventually, so don't worry. The first thing we are going to do is get your console up. The console is a part of your browser's developer tools.

The way you bring up your browser developer tools is by fiddling with your browser's menus or by using the more handy keyboard shortcuts. Depending on your browser and platform, your developer tools will each look a little different. The important thing is to find the Console tab and make sure the console gets displayed. The thing I want to highlight is that it doesn't matter which browser you use. The console looks and functions pretty much the same on all of them.

Just bring up the console in your favorite browser, and get ready to start actually using the console in the following sections. Now, you can totally just passively read the following sections and learn a whole bunch of console-related things without lifting a finger. If that is what you would like to do, then skip all of this and jump to the next section :P. What we have here is a really simple HTML page with a button that you can click.

When you click on the button, an alert dialog the same one we described earlier will appear. In the following sections, we'll modify this example to help bring some of the console-related things to life! The first thing we are going to do is tell our console to display things on screen.