JavaScript: Everyday Utilities and Recipes

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Table Of Content

· String
∘ isString
∘ Generate UUID
· Math
∘ isNumber
∘ Random Numbers
∘ Reverse Number
· Array
∘ Remove Duplicate values from an Array
∘ Concat one array to another, without creating a new one.
∘ Shuffle an array
∘ Generate and Fill Array
· Object
∘ Mixin
∘ Object to Map
∘ Map to Object

String

isString

function isString(value) {
   return typeof value === "string" || value instanceof String;
}

/* TEST */
console.log(isString("abc") === true);
console.log(isString(new String("abc")) === true); // just typeof value === "string" will miss the String Objects

Generate UUID

window.crypto.randomUUID() // '95a1faba-54c3-498f-8e9f-30968cc5d93f'

Math

isNumber

function isNumber(value) {
    return typeof value === "number" && isFinite(value);
}

isNumber(10); // true
isNumber(5.1); // true
isNumber(NaN); // false, just typeof value === "number" will fail here

Random Numbers

Simple: Simple Random Number Generator (Good for most of the cases)

const genRandomNumbers = (max, min = 0) => {
    const baseRandomNo = Math.floor(Math.random() * (max - min));
    return min + baseRandomNo;
};

genRandomNumbers(10); // any number between 0 <= no < 10
genRandomNumbers(10, 5);// any number between 5 <= no < 10

It’s important to understand that numbers generated by Math.random() are pseudorandom, which means they can be guessed or reverse engineered. They are not random enough for cryptography, lotteries, or complex modeling

Advanced: A true random number generator

const genRandomNumbers = (max, min = 0) => {
    const randomBuffer = new Uint32Array(1);
    window.crypto.getRandomValues(randomBuffer); // Replace it with crypto module in NodeJs
    const [randomNo] = randomBuffer; // No between 0 - 2^32
    const randomFraction = randomNo / (0xffffffff + 1);
    const randomNumber = Math.floor(randomFraction * (max - min)) + min;

    return randomNumber;
};

genRandomNumbers(10); // any number between 0 <= no < 10
genRandomNumbers(10, 5); // any number between 5 <= no < 10

Reverse Number

Array

Remove Duplicate values from an Array

Concat one array to another, without creating a new one.

Shuffle an array

Using Fisher-Yates shuffle Algorithm

Generate and Fill Array

Object

Mixin

Object to Map

Map to Object