DEV Community: Anders Persson

A book about Javascript...

Anders Persson — Sun, 27 Aug 2023 19:42:55 +0000

Start reading the book "Mordern JavaScript for the Impatient", as a quick update of my old javascript knowledge to day version, soo far a good book.

The lines got me to start thinking...

“Any application that can be written in JavaScript, will eventually be written in JavaScript.”

Jeff Atwood

Here i think is some prof..
https://demo.os-js.org/

Play safe without Try Catch...

Anders Persson — Sun, 20 Aug 2023 23:12:59 +0000

The most dangerous thing you can do, in programming (besides running out of coffee) is type conversion, especially when you run on so-called "happy flow", which means that you always think nothing can go wrong, it's better to always think that it can go wrong and writes its code after that. Example: conversion of a text to integers, i.e. we get the numbers as text.

string payment = "100.5"
var amount = double.Parse(payment);

above work well, until one day when we get..

string payment = "saknas";
var amount = double.Parse(payment);

This gives a exception and program stops.

So can we find out when our "payment" is not correct?
Yes, you can put a try catch around, but it will be a lot of code, there is one easier way, with .. TryParse

string payment = "saknas"

if( !double.TryParse(payment, out amount)) 
{
  handling error, write to log!
}

TryParse returns true if the conversion went well, and false if it went wrong, without throwing an error that causes your program to stop. Now you can easily take care of the error, without having to write a lot of try-catch handling for it.

Happy coding!
Anders

Heard about DENO?

Anders Persson — Sat, 19 Aug 2023 16:55:54 +0000

Disclaimer; I'am a backend developer, and try to keep up with frontend, so this (my first) article can be basic for many frontend developers.

Deno has the same creator as NODEJS (Ryal Dahl), Deno was a project started because Ryal had many things he learned working with Nodejs, and like to change, but it was easier to start over.

Focus in Deno is Security, and it is ALL CLOSED BY DEFAULT, so a script has to get ok, for write, read .. , and latest version access can be set on domain level.

Another big thing is DENO doesn't have a package handler, like node, you don't download stuff, you access them the same way as you do in webpages. But.. to make transit from Node easy today Deno understands NPM, so you can slowly rewrite if you like.

But, the big thing for me is deno runs TypeScript out-of-the-box, without setting up anything, just have an .ts extension and you can do a

deno run myscript.ts

of course

deno run myscript.js

for javascript works to.

Example myscript.js

console.log("Hello World");

Example myscript.ts

function addHello(data: string) {
    return `Hello ${data}`;
}
console.log(addHello("World"));

But there is another nice thing, you can write scripts for terminal, and make a standalone binary, which runs without deno, but don't forget to allow access rights, like if your script likes to read a folder, else it will not be allowed to do this.

deno compile myscript.ts

Om my windows machine it gives me a myscript.exe
This is just a scratch what Deno can do, read more at deno homepage
Link: deno.land

Happy hacking!
Anders