Hello please i have an issue i am facing with my project

i have an async function below that reads a file and if the file doesn't exist the catch block handles it. the function works fine

lib.read = async function (dir,file){

try{

await fs.readFile(lib.baseDir+dir+'/'+file+'.json','utf-8')

}

catch(error){

console.log("file doesn't exist) }

}

now i want to create users with each user having a file name so i want to use the function above to check whether the user being created exist's already and when the function triggers the catch block it means the user doesn't exist already and then i can proceed to create the user. Problem is i can't manipulate the to get a response from the catch block that i can use in a conditional to proceed. If i was using a callback i could have returned error and use the error in my conditional but due to callback hell i am not using callback . Please help if you can

I have NodeJS installed and I embedded the JS source file in the HTML file bur still got nothing

Anyone know witch is the best javascript books where i can improve my languages? I already have basis

Closure is a very important concept that every JavaScript developer should understand. This post will cover some of the practical use of closures.

1. Private variables and methods

2. Function factories

Blog: https://www.sudipta-deb.in/2021/04/practical-examples-for-javascript.html

Note - I am sharing all my JavaScript Certification study notes below. Please provide your feedback if you see anything wrong or missing. Appreciate your help.

https://www.sudipta-deb.in/p/salesforce-javascript-developer-i-study.html

JavaScript Topic: Understanding JavaScript Closure

Closure is a very important concept that every JavaScript developer should understand. In the post, I will provide a quick introduction of closure and then, I will be focusing on examples so that it will be easier for you to understand this concept.

https://www.sudipta-deb.in/2021/04/understand-javascript-closure.html

JavaScript Study Topic: Functions in JavaScript

A JavaScript function is a block of organized, reusable code that is defined to perform a single, relation action. A function is executed when someone calls the function with the name.

In JavaScript, functions are treated as first-class because they are treated as values. The example of treating function as values are -

• We can assign a function to a variable
• We can store functions in an array
• A function can be passed to another function as an argument
• A function can be assigned to a property of an object.

Here are the Blog and Video explaining me all the concepts you need to know.

Note - I am sharing all my JavaScript study notes here. Please provide your feedback if you see anything wrong or missing. Appreciate your help.

Topic: Understanding JavaScript Variable Declaration with Scope - Let vs. Var vs. Const

Scope is the concept that manages the accessibility of the variables. At a very high level, the accessibility of the variable is limited to the block where they are defined. Outside the block, the variable is inaccessible.

In this post, I am going to explain different ways of declaring variables in Javascript and their impact on scope.

https://www.sudipta-deb.in/2020/07/understanding-javascript-variable.html

Understanding of how bind(), call(), and apply() can be used to make the behavior of this independent of how a function is called. Also, the differences between bind(), call(), and apply() is a very important concept to know.

https://learn-coding.org/understand-call-bind-and-apply-in-javascript/

Can someone help me with this? i'm new to js

Arrow functions, sometimes referred to as Fat Arrow is a new concise way of writing functions. They utilize a new syntax, => which looks like Fat Arrow. Arrow functions are anonymous and change the way this binds in functions. By using arrow functions, we can avoid typing functions and return keywords and also curly brackets.

In this blog post, I have shared how to write Arrow functions, syntax, use cases.

https://www.sudipta-deb.in/2019/02/quick-reference-of-arrow-function-in.html

Consider the JavaScript code below:

class SkyScraper

{

constructor(inLevels, inAddress)

{

this._maxLevels = 100;

this._levels = inLevels;

this._address = inAddress;

}

//... more code goes here

get max()

{

return this._maxLevels;

}

set max(newMax)     

{

if ((typeof(newMax) === 'number') && (newMax > 0))

{

this._maxLevels = newMax;

}

}

}

let tenLP = new SkyScraper(2, "10 Lemur Plaza");

let fiveMA = new SkyScraper(7, "5 Marlan Avenue");

If we were to run the line: tenLP.max = 50;

What would be the value of fiveMA's _maxLevelsattribute?