Unknown console API in JS

Are you a fan of console.log when you debug (instead of using debugger)? Or you want to make better logging for your scripts / applications?

You are in the right place! In this article, I gonna show you some console methods that you probably don't know that are going to make your logs better :)

Log with style: console.log

Okay, I'm sure you know this one. But did you know you can stylized your text.
You can do this by putting %c and defining the style in the following parameter (inline css format) before the text you want to stylize.

console.log(  "%c This is a stylized text",  "color:red;text-decoration: underline;");

Note: You can put multiple different stylized text in a same log:

console.log(  "%c This is a red text %c and a blue text",  "color:red",  "color:blue");

Note: You can do it with other logging function like info, debug, warn and error.

Make a quick counter: console.count

How many times when doing React you wanted to see how many times a component renders? Yep you can see it with the React Developper Tools but it's not enough quick for me :)
So you can make a counter thanks to console.count:

function MyComponent() {  console.count("Render counter");  return <p>A simple component</p>;}

Note: The label is optional, by default it will be "default".

Log error with assertion: console.assert

If you want to display an error message when a specific assertion is false you can use console.assert:

const useMyContext = () => {  const myContextValues = useContext(MyContext);  // You probably want to throw an error if it happens  // It's only an example  console.assert(    myContextValue === undefined,    "useMyContext has to be used below MyProvider"  );  return myContextValues;};

Full description of elements: console.dir

console.dir allows you to show a better description of objects. For example when you console.log a function it will only stringify the function, but with console.dir it will show you all properties:

function myMethod() {}console.dir(myMethod);

Improve readability: console.group

If you have a lot of logs, it can be difficult to keep track of all these logs. Fortunately, console.group is here for you.

function myMethod() {  console.group("My method optional label");  console.log("Log that will be group");  console.info("With this one");  console.error("And this one too");  console.groupEnd("My method optional label");}myMethod();console.log('Outside log');

Note: It's possible to nest console.group. The label is totally optional but can really help you for debugging.

Make a nice table: console.table

If you want to display data inside a table, you can do it with console.table. The first parameter is the data to display (an array or object). The second one is the columns to display (optional parameter).

console.table(  [    {      name: "First algo",      duration: "3.2s",      other: "Hello",    },    {      name: "Second algo",      duration: "4.1s",      other: "Guys and girls",    },  ],  ["name", "duration"]);

Make timers: console.time

When you want to see how long a method takes to run you can use performance.now() otherwise even easier console.time(), console.timeEnd() and console.timeLog():

function myMethod() {  console.time("A label");  // Do some process  // If you want to log the time during the process  console.timeLog("A label");  // Other process  // Will print how long the method takes to run  console.timeEnd("A label");}myMethod();

Note: The label is optional, it will have the "default" label. You cannot start a timer with the same label than already running one.

Display stacktrace: console.trace

If you want to know where is called your function then console.trace is your friend and will display the stack trace:

function children() {console.trace('Optional message');}function parent() { children();}parent();

What is your favorite console command?
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