javascript-tricks

Arrays

Union of arrays

let a = [1, 2, 3, 4, 5];
let b = [3, 4, 5, 6, 7];

let result = [...new Set([...a, ...b])]; // [1, 2, 3, 4, 5, 6, 7]

Intersection of arrays

let a = [1, 2, 3, 4, 5];
let b = [2, 3, 4, 6];

let result = a.filter(val => ~b.indexOf(val)); // [2, 3, 4]

Get non intersected values

let a = [1, 2, 3, 4, 5];
let b = [2, 3, 4, 6];

let result = a.filter(val => !~b.indexOf(val)); // [1, 5]

Printing array of array values in a new line

const a = [
  [11],
  [7, 15],
  [5, 9, 13, 20],
  [3, 6, 8, 10, 12, 14, 18, 25]
];
const result = a.reduce((el, acc) => el + acc.join(' ') + '\n', '\n');

// output
/*
  11
  7 15
  5 9 13 20
  3 6 8 10 12 14 18 25
*/

Removing duplicates from an array


/*
 #method 1
*/

  let fruits = ['banana','mango','apple','sugarcane','mango','apple']

  let uniqueFruits = Array.from(new Set(fruits));

 // uniqueFruits -- [ 'banana', 'manago', 'apple', 'sugarcane' ]

/*
 # method 2
*/

  let uniqueFruits2 = [...new Set(fruits)];

  // uniqueFruits2 -- [ 'banana', 'manago', 'apple', 'sugarcane' ]

Replace the specific value in an array

    var fruits2 = [...fruits];

    fruits2.splice(0,2,"potato","tomato");

    // fruits2  ['potato', 'tomato', 'apple', 'sugarcane', 'manago', 'apple' ]

Mapping array without maps


  let friends = [
      {name:"John", age:22},
      {name:"Peter", age:23},
      {name:"bimbo",age:34},
      {name:"mark",age:45},
      {name:"Esther",age:21},
      {name:"Monica",age:19}
  ];

  let friendNames = Array.from(friends,({name})=>name);

  // friendNames --   ['John', 'Peter', 'bimbo', 'mark', 'Esther', 'Monica' ]

Emptying an array

  let fruits = ['banana','mango','apple','sugarcane','mango','apple']

  fruits.length = 0;

  // fruits -- []

Convert an array to an object

   let fruits = ['banana','manago','apple','sugarcane','manago','apple']

   const fruitsObj = {...fruits};

   //  fruitsObj --  {'0': 'banana','1': 'mango', '2': 'apple','3': 'sugarcane','4': 'mango','5': 'apple'}

### Fulfill array with data

  let newArray = new Array(10).fill("1");

  // newArray -- ['1', '1', '1', '1','1', '1', '1', '1','1', '1']

Merging Arrays

  let fruits = ['banana','manago','apple'];
  let meat = ["Poultry","beef","fish"]
  let vegetables = ["Potato","tomato","cucumber"];
  let food = [...fruits,...meat,...vegetables];

  // food  -- ['banana',  'manago','apple',   'sugarcane','manago',  'apple','Poultry', 'beef','fish',    'Potato','tomato',  'cucumber']

Merging only duplicates value in two arrays

    let numOne = [0,2,4,6,8,8];
    let numTwo = [1,2,3,4,5,6];

    const duplicatedValue = [...new Set(numOne)].filter(item=>numTwo.includes(item));
    // duplicatedValue -- [ 2, 4, 6 ]

Remove falsy value from an array.

    const mixedArray = [0,"blue","",NaN,true,undefined,"white",false];
    const filteredArray = mixedArray.filter(Boolean);

    // filteredArray -- [ 'blue', true, 'white' ]

Reverse an array

  const colors = ['blue','red','green','black'];

  const reverseColors = colors.reverse();
  // reverseColors  -- [ 'black', 'green', 'red', 'blue' ]

Sum of the value in an array

  const val = [1,4,5,7];

  const valSum = val.reduce((x,y)=>x+y);

  // valSum --  17

Generate an array from a function Arguments

 function f() {
    return Array.from(arguments);
  }
  f(1,2,4))

  // result -- [1,2,4]

Strings

Reverse a string

let str = str.split('').reverse().join('');

Replace a character at a particular index

function replaceAt(str, i, char) {
  return s.substring(0, i) + char + str.substring(i + 1);
}

Remove last character in a string


javascript

// using substring
str.substring(0, str.length - 1);

// using slice
str.slice(0, -1)

Blog

AmnaAbd

Arrays

Union of arrays

Intersection of arrays

Get non intersected values

Printing array of array values in a new line

Removing duplicates from an array

Replace the specific value in an array

Mapping array without maps

Emptying an array

Convert an array to an object

Merging Arrays

Merging only duplicates value in two arrays

Remove falsy value from an array.

Reverse an array

Sum of the value in an array

Generate an array from a function Arguments

Strings

Reverse a string

Replace a character at a particular index

Remove last character in a string

Join Our Newsletter. No Spam, Only the good stuff.

Related