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Javascript best practicesđŸ”„

 2 years ago
source link: https://dev.to/devsimc/javascript-best-practices-44ll
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  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

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 

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!"

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