Hash Tables? How to avoid IF/Switch in JS

juanpumpkinpie — Wed, 01 Dec 2021 21:00:18 +0000

Easily they are associative data structures that allow you to create list paired values, retrieving from the key.

Why to use them?
Because is more fast to: space, search, insertion and delete operations. Javascript Object is the sample of hash tables.

let Obj = {
Juan: "developer",
Shellby: "recruiter"
}

Javascript has implemented a way to approach the hash tables using map to store the data.

const newCollection = new Map();
newCollection.set("Juan", "developer"); // Paired
newCollection.set("Marina", "developer");
newCollection.set("Shellby", "recruiter"); // Paired

console.log(newCollection.get("Juan")); // -> Developer
console.log(newCollection.size); // -> 3

So, as you can see above, Map use get and set to pair the Object. But as difference using Map you can't overwrite their values because it violates the inherited method property hasOwnProperty().

How to IMPLEMENT a Hash Table Data Structure in Javascript?
Let's make an exercise with Marvel Comic characters vs. Characters. Implement a logic to define who wins a fight between 'Loki' character assuming who's attacking:

attack	Loki must be:
Iron-Man	Magneto
Thor	Odin
Hulk	Thanos
Wolwerine	Magneto

Here is the answer. Usually you could follow this pattern generated by:

const attack = "Iron-Man";
const Loki = "";

if(attack === 'Iron-Man'){
 loki = 'Magneto'; //-> Loki custom as Magneto;
}else if(attack === 'Hulk'){
 loki = 'Thanos';  //-> Loki custom as Thanos;
}..etc..
else{
loki='loki';
}

In this point, many developers can to think about refactor to switch because it works as:

switch(attack){
   case 'Iron-Man':
   loki = 'Magneto'
   break;

   default:
   Loki = 'Loki'

(.. so on)...
}

Implementation HashTable:
You could use attack as index for the hash table to recover the value and refactor as clean code below:

const attack = 'Hulk'

const LOKI_CUSTOM = {

'Iron-Man': 'Magneto',
 Thor: 'Odin',
 Hulk: 'Thanos',
}

const LOKI_DEFAULT = 'Loki'
const loki = LOKI_CUSTOM[attack] || LOKI_DEFAULT

console.log(loki) -> Thanos

It also allow you to export and re-use the object, and it can be implemented with methods and ternary functions! e.x:

const LOKI_CUSTOM = {

'Iron-Man': () => 'Magneto',
 Thor: () => 'Odin',
 Hulk: () => 'Thanos',
}

const loki = LOKI_CUSTOM[attack]
 ? LOKI_CUSTOM[attacks]()
 : LOKI_DEFAULT

React Prot-Types and Errors

juanpumpkinpie — Wed, 20 Jan 2021 15:41:19 +0000

Guys, is important to add the prop-types for the apps you are developing to avoid problems in the UI render, because if the app start to growing up, the errors also can do it.
Here I attach sample,

https://es.reactjs.org/docs/typechecking-with-proptypes.html

Besides, it is important handle the errors, and to know what is happening back the app in the modeling, structure and behave: https://es.reactjs.org/blog/2017/07/26/error-handling-in-react-16.html

componentDidCatch is more important than a simple Try,Catch, check the documentation and improve your code!

Steps to create a SSH-key

juanpumpkinpie — Fri, 18 Sep 2020 08:38:07 +0000

In this vlog I found a good way to control repositories with the shh-key, but the most important, works for CTF365 Capture the flag! (Swietnie).

DEV Community: juanpumpkinpie

Hash Tables? How to avoid IF/Switch in JS

React Prot-Types and Errors

Steps to create a SSH-key