How console.log(object) works in background?

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I have this code:

const obj = {name: 'maro', age: 77}

console.log(obj); // it logs { name: 'maro', age: 77 }

It seems like evident! but I want to know how console.log internally works ? which methods of "obj" it calls to get the "{ name: 'maro', age: 77 }"

obj contains those properties:

obj.__defineGetter__      obj.__defineSetter__      obj.__lookupGetter__      obj.__lookupSetter__      obj.__proto__             obj.constructor           obj.hasOwnProperty
obj.isPrototypeOf         obj.propertyIsEnumerable  obj.toLocaleString        obj.toString              obj.valueOf    obj.age        obj.name

But none of them returns "{ name: 'maro', age: 77 }"!

even obj.toString() returns '[object Object]'


As you can see in Node.js console.log documentation, it uses, behind the scenes, util.format to format its output.

According to util.format documentation, it returns a string representation of an object with generic JavaScript object formatting, similar to util.inspect.

You can see its actual implementation, at least for Node.js, here: https://github.com/nodejs/node/blob/75dc8938a40100a53323ed87159a1ab2f149ceca/lib/internal/util/inspect.js#L1567. Have fun reading this code :)

Console object - console - Web APIs, The console object provides access to the browser's debugging console The specifics of how it works varies from browser to browser, but there is a de console.assert(): Log a message and stack trace to console if the first argument "color: yellow; font-style: italic; background-color: blue;padding: 2px");. The console.log() is a function in JavaScript which is used to print any kind of variables defined before in it or to just print any message that needs to be displayed to the user. Syntax: console.log(A); Parameters: It accepts a parameter which can be an array, an object or any message. Return value: It returns the value of the parameter given.


It is obj.valueOf() if I'm not mistaken. Here is the documentation: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/valueOf

How to get the most out of the JavaScript console, window.console.log('This works'); console.log('So does this'). The second option is The most common element of the console object is console.log . For most Though warn does have a yellow background in Chrome. console.log(`This is a string: ${'string'}`); console.log(`This is a number: ${42}`); console.log(`This is an object: ${{object: 'object'}}`); Chrome template literal examples Notice that the object is handled a bit better with the string substitution, so pick the appropriate choice for your requirements.


You can use valueOf().

const object1 = {name:"ankit",age:27}
console.log(object1.valueOf());

Note: Objects in string contexts convert via the toString() method, which is different from String objects converting to string primitives using valueOf. All objects have a string conversion, if only "[object type]". But many objects do not convert to number, boolean, or function.

How to use the JavaScript console: going beyond console.log(), console.log('Is this working?'); The most intuitive way to log this is to just console.log(variable) one after the other. Whenever you have objects with common properties or an array of objects use console.table() . 'Get user details ');console.log('%c Error ', 'color: white; background-color: #D33F49', 'Error� I recently ran into issues with console.log while running the most recent preview build of Windows 10. Below is the code I was trying to log. The log would say my objects functions, proto, and users were undefined. I could "work around" this by changing my version of IE to 9 or putting a breakpoint on console.log().


If you need the name 'maro' and the age 77, you need use obj.name and obj.age...

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Use JavaScript console.log() like a PRO - novice2pro, Using console.log() for JavaScript debugging is one of the most common ' background: black; color: red');console.log('%c Log Message 3 with Tip: You can also use Ctrl + L shortcut to clear the console and it works in all the browsers. The table method can be used to display an array or an object in a� Use console.log(JSON.stringify(result)) to get the JSON in a string format.. EDIT: If your intention is to get the id and other properties from the result object and you want to see it console to know if its there then you can check with hasOwnProperty and access the property if it does exist:


Beyond console.log() - Matt Burgess, While most people use it as console.log(object) , you can also do console.log( object, This works a lot like something like sprintf in C or PHP. console.log('I am a %cbutton', 'color: white; background-color: orange; padding:� console.log(object [, object, …]) Lets start by looking at one of the most commonly used console methods, console.log(). This method simply outputs an object to the console. console.log('Hello Treehouse'); If you list multiple objects they will be concatenated into a single, space-delimited string, which is then output to the console.


Get Started With Logging Messages In The Console, Figure 12. A group of messages in the Console. Click Log Custom. A message with a red border and blue background gets logged to� You cannot always trust information reported by console.log() because there is simply no standardized behavior about it. You don’t really know what happens under the hood. Most of the time calling console.log() when the console is not yet active only results in a reference to the object being queued, not the output the console will contain. As a workaround you will need to either clone the information or serialize snapshots of it.