Javascript tips and tricks Javascript best practices 2022

Javascript tips and tricks Javascript best practices 2022

1. Declare and Initialize Arrays in javascript

2. Find out the sum, minimum and maximum value in javascript

3. Sorting Array of String, Numbers or Objects in javascript 

4. Remove Duplicates array values in javascript

5. Create a Counter Object or Map in javascript

6. Ternary Operator in javascript

7. Arrow Functions in javascript

8. Shuffle an Array in javascript

9. Rest & Spread operators in javascript 

10. Convert Decimal to Binary or Hexa in javascript

Useful techniques to reduce the lines of code

1. Declare and Initialize Arrays in javascript 

We can initialize array of particular size with default values like "", null or 0. You might have used these for the 1-D array but how about initializing 2-D array/matrix?

const array = Array(5).fill(''); 

// Output 

(5) ["", "", "", "", ""]

const matrix = Array(5).fill(0).map(()=>Array(5).fill(0)); 

// Output

(5) [Array(5), Array(5), Array(5), Array(5), Array(5)]

0: (5) [0, 0, 0, 0, 0]

1: (5) [0, 0, 0, 0, 0]

2: (5) [0, 0, 0, 0, 0]

3: (5) [0, 0, 0, 0, 0]

4: (5) [0, 0, 0, 0, 0]

length: 5

2. Find out the sum, minimum and maximum value in javascript

const array  = [5,4,7,8,9,2]; 

Sum in array javascript

array.reduce((a,b) => a+b);

// Output: 35

MAX in array javascript

array.reduce((a,b) => a>b?a:b);

// Output: 9

MIN in array javascript

array.reduce((a,b) => a<b?a:b);

// Output: 2

3. Sorting Array of String, Numbers or Objects in javascript 

Sort String Array in javascript

const stringArr = ["Joe", "Kapil", "Steve", "Musk"]

stringArr.sort();

// Output

(4) ["Joe", "Kapil", "Musk", "Steve"]

stringArr.reverse();

// Output

(4) ["Steve", "Musk", "Kapil", "Joe"]

Sort Number Array in javascript

const array  = [40, 100, 1, 5, 25, 10];

array.sort((a,b) => a-b);

// Output

(6) [1, 5, 10, 25, 40, 100]

array.sort((a,b) => b-a);

// Output

(6) [100, 40, 25, 10, 5, 1]

 

4. Remove Duplicates array values in javascript

const array  = [5,4,7,8,9,2,7,5];

array.filter((item,idx,arr) => arr.indexOf(item) === idx);

// or

const nonUnique = [...new Set(array)];

// Output: [5, 4, 7, 8, 9, 2]

5. Create a Counter Object or Map in javascript

let string = 'kapilalipak';

const table={}; 

for(let char of string) {

  table[char]=table[char]+1 || 1;

}

// Output

{k: 2, a: 3, p: 2, i: 2, l: 2}

 

6. Ternary Operator in javascript

function Fever(temp) {

    return temp > 97 ? 'Visit Doctor!'

      : temp < 97 ? 'Go Out and Play!!'

      : temp === 97 ? 'Take Some Rest!';

}

// Output

Fever(97): "Take Some Rest!" 

Fever(100): "Visit Doctor!"

7. Arrow Functions in javascript

const person = {

name: 'Krishna',

sayName() {

    return this.name;

    }

}

person.sayName();

// Output

"Krishna"

8. Shuffle an Array in javascript

const list = [1, 2, 3, 4, 5, 6, 7, 8, 9];

list.sort(() => {

    return Math.random() - 0.5;

});

// Output

(9) [2, 5, 1, 6, 9, 8, 4, 3, 7]

// Call it again

(9) [4, 1, 7, 5, 3, 8, 2, 9, 6]

9. Rest & Spread operators in javascript 

function myFun(a,  b, ...manyMoreArgs) {

   return arguments.length;

}

myFun("one", "two", "three", "four", "five", "six");

// Output: 6

10. Convert Decimal to Binary or Hexa in javascript 

const num = 10;

num.toStrin

 

g(2);

// Output: "1010"

num.toString(16);

// Output: "a"

num.toString(8);

// Output: "12"