Introduction

In JavaScript, an array is a special variable that is used to store different elements. It has some built-in properties and methods we can use to add, remove, iterate, or manipulate data following our needs. Knowing JavaScript array methods can lift your skills as a developer.
Array Min Max
The below example shows how to find the minimum and maximum values in an array
  1. var numbers = [5, 458 , 120 , -215 , 228 , 400 , 122205, -85411];
  2. var maxInNumbers = Math.max.apply(Math, numbers);
  3. var minInNumbers = Math.min.apply(Math, numbers);
Shortcut for declaring numbers 1-100 in an Array
The below code shortens manual entry of 1-100 in array. It results in numbers = [1,2,3 ,... 100]
  1. var numbersArray = [] , max = 100;
  2. for( var i=1; numbersArray.push(i++) < max;);
Remove an array element without mutating the original array
The below code doesn't alter the orginal array and produces the results as mammals that will be equal to ['squirrel', 'bear', 'deer', 'rat']
  1. const animals = ['squirrel', 'bear', 'deer', 'salmon', 'rat'];

  3. const mammals = [...animals.slice(0,3), ...animals.slice(4)];
Joining 2 Arrays
The below code Joins two arrays and produces the result as combined = [1, 2, 3, 4, 9, 10, 5, 6, 7, 8]
  1. var spreadableOne = [1, 2, 3, 4,9,10];
  2. var spreadableTwo = [5, 6, 7, 8];
  3. var combined = [...spreadableOne, ...spreadableTwo];
Object into a Sub-Array
The below code converts the object into a sub-Array
  1. const weather = {
  2. rain: 0,
  3. temperature: 24,
  4. humidity: 33,
  5. }
  6. const entries = Object.entries(weather);
Split the string into an array
The below code converts a string into an Array
  1. const newArray = Array.from('hello');
Joining Array values to a string
The below code joins an array into a specified string format
  1. var elements = ['Fire', 'Wind', 'Rain'];
  2. console.log(elements.join());
  3. // expected output: Fire,Wind,Rain
  4. console.log(elements.join(''));
  5. // expected output: FireWindRain
  6. console.log(elements.join('-'));
  7. // expected output: Fire-Wind-Rain
Concating 2 Arrays
The below code joins 2 Arrays using the Concat operator
  1. var array1 = ['a', 'b', 'c'];

  3. var array2 = ['d', 'e', 'f'];

  5. console.log(array1.concat(array2));

  7. // expected output: Array ["a", "b", "c", "d", "e", "f"]
Merging an Array with an existing element
The below code merges an array with a specified element. The expected result will be ["$2", "$3", "$4", "$5"]
  1. const numbers = [2, 3, 4, 5];

  3. const dollars = numbers.map( number => '$' + number);
Unique Array
The below code removes the duplicates and provides a unique array. The expected result is [1, 3, 2, 5, 4, 8]
  1. function uniteUnique(arr)
  2. {
  3. var args = Array.from(arguments);
  4. var newArr = [];
  5. for (var k = 0; k < args.length; k++)
  6. {
  7. newArr = newArr.concat(args[k]);
  8. }
  9. for (var i = 0; i < newArr.length; i++)
  10. {
  11. for (var j = i + 1; j < newArr.length; j++)
  12. {
  13. if (newArr[i] === newArr[j])
  14. {
  15. newArr.splice(j, 1);
  16. i--;
  17. }
  18. }
  19. }
  20. return newArr;
  21. }
  23. uniteUnique([1, 3, 2], [5, 2, 1, 4], [8, 1]);
Flattening Array of Arrays
The below code destroys the multiple sub arrays into single array. The expected output is [1, 2, 3, "ab", 4, 5, 6, 7, 8, 9, "da"]
  1. const aoa= [[1,2,3,"ab"],[4,5,6],[7,8,9,"da"]];
  2. const flatteredArr = aoa.reduce((acc,arr) => [...acc , ...arr]);
Searching the Array element by value
(Case Insensitive)
The below code searches the value by name, which contains li whether its capitalized or not
  1. const employees = [
  2. { id: 101, name: 'john', group: 'tech-lead' },
  3. { id: 102, name: 'sam', group: 'associate' },
  4. { id: 103, name: 'danny', group: 'senior associate' },
  5. { id: 104, name: 'ketty', group: 'senior associate' },
  6. { id: 105, name: 'mili', group: 'junior' },
  7. { id: 106, name: 'mouLi', group: 'senior associate' },
  8. { id: 107, name: 'George', group: 'senior associate' }
  9. ];

  11. let res = employees.filter(it => new RegExp('li', "i").test(it.name));
(Case Sensitive)
The below code searches the value by name which contains li, strictly case sensitive.
  1. const employees = [
  2. { id: 101, name: 'john', group: 'tech-lead' },
  3. { id: 102, name: 'sam', group: 'associate' },
  4. { id: 103, name: 'danny', group: 'senior associate' },
  5. { id: 104, name: 'ketty', group: 'senior associate' },
  6. { id: 105, name: 'mili', group: 'junior' },
  7. { id: 106, name: 'mouLi', group: 'senior associate' },
  8. { id: 107, name: 'George', group: 'senior associate' }
  9. ];

  11. let res = users.filter(it => it.name.includes('li'));
Splitting Odd and Even numbers
The below code splits the odd and even numbers into separate arrays
  1. const numbers = [1,2,3,4,5,6,7,8,9];
  3. const { evenNumbers, oddNumbers} = numbers.reduce((obj,number) => {
  4. if( number % 2 === 0)
  5. {
  6. obj.evenNumbers.push(number);
  7. }
  8. else
  9. {
  10. obj.oddNumbers.push(number);
  11. }
  13. return Object.assign({},obj);
  14. },{
  15. evenNumbers : [],
  16. oddNumbers : []
  17. });
  19. console.log(evenNumbers); // (4) [2,4,6,8]
  20. console.log(oddNumbers); // (5) [1,3,5,7,9]
Grouping the Array count
The below code get the number of employees in each group, expected output tech-lead: 1, associate: 1, senior associate: 4, junior: 1
  1. const employees = [
  2. { id: 101, name: 'john', group: 'tech-lead' },
  3. { id: 102, name: 'sam', group: 'associate' },
  4. { id: 103, name: 'danny', group: 'senior associate' },
  5. { id: 104, name: 'ketty', group: 'senior associate' },
  6. { id: 105, name: 'mili', group: 'junior' },
  7. { id: 106, name: 'mouli', group: 'senior associate' },
  8. { id: 107, name: 'George', group: 'senior associate' }
  9. ];
  10. // In the above example, we need to get the number of employees in each group. At first,
  11. // it looks difficult but you can easily achieve that by using the below code:
  13. const employeesByGroup = employees.reduce((acc, employee) => {
  14. acc[employee.group] = acc[employee.group] + 1 || 1;
  15. return acc;
  16. }, {});
  18. console.log(employeesByGroup); // tech-lead: 1, associate: 1, senior associate: 4, junior: 1}
Current timezone Isostring
The below method returns the current timezone Isostring
  1. var now = new Date(); // Thu Jan 16 2020 18:00:37 GMT+0530 (India Standard Time)

  3. var isoDate = new Date(now.getTime() - now.getTimezoneOffset() * 60000).toISOString()//2020-01-16T18:00:26.392Z

Conclusion

I hope these snippets can help everyone with their development. Happy Coding :)