Array

Arrays are Objects. The type of operator in JavaScript returns "object" for arrays. But, JavaScript arrays are best described as arrays. Arrays use numbers to access their "elements".

• Example:

  const num= ['1', '2', '3'];

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Creating an Array

Using an array literal is the easiest way to create a JavaScript Array.

• Syntax:

  const array_name = [item1, item2, ...];

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How to access element of an array:

We can access the elements of an array using its index(index starts with 0).

• Example

  let num = ['1', '2', '3', '4'];
  console.log("2nd element in array is: ", num[1]);
  

  Output:

  2nd element in array is: 2

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JavaScript Array Methods

Converting Arrays to Strings

The JavaScript method toString() converts an array to a string of (comma separated) array values.

• Example

  let num = ['1', '2', '3', '4'];
  console.log(num.toString());
  

  Output:

  1,2,3,4

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JavaScript Array pop()

The pop() method removes the last element from an array:

• Example

  let num = ['1', '2', '3', '4'];
  let popped = num.pop()
  console.log("The array after pop last element: ", num);
  console.log("The pop element is: ", popped);
  

  Output:

  The array after pop last element: [ '1', '2','3' ]

  The pop element is: 4

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JavaScript Array Push()

The push() method adds a new element to an array (at the end):

• Example

  let num = ['1', '2', '3', '4'];
  let pushed = num.push("5")
  console.log("The new array is: ", num);
  console.log("The element pushed is: ", pushed);
  

  Output:

  The new array is: [ '1', '2', '3', '4', '5' ]

  The element pushed is: 5

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JavaScript Array shift()

The shift() method removes the first array element and "shifts" all other elements to a lower index.

• Example

  let num = ['1', '2', '3', '4'];
  let shifted = num.shift()
  console.log("The new array is: ", num);
  console.log("The element shifted is: ", shifted);
  

  Output:

  The new array is: [ '2', '3', '4' ]

  The element shifted is: 1

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JavaScript Array unshift()

The unshift() method adds a new element to an array (at the beginning), and "unshifts" older elements:

• Example

  let num = ['1', '2', '3', '4'];
  let unshifted = num.unshift('0');
  console.log("The new array is: ", num);
  

  Output:

  The new array is: [ '0', '1', '2', '3', '4' ]

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Changing Elements

Array elements are accessed using their index number:

Array indexes start with 0:

[0] is the first array element

[1] is the second

[2] is the third ...

• Example

  let num = ['1', '2', '3', '4'];
  num[3] = 'xyz';
  console.log("The new array is: ", num);
  

  Output:

  The new array is: [ '1', '2', '3', 'xyz' ]

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JavaScript Array length

The length property provides an easy way to append (insert element at last) a new element to an array:

• Example

  let num = ['1', '2', '3', '4'];
  num[num.length] = '5';
  console.log("The new array is: ", num);
  

  Output:

  The new array is: [ '1', '2', '3', '4', '5' ]

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Concatenate Arrays

The concat() method creates a new array by merging (concatenating) existing arrays:

• Example-1

  let num = ['1', '2', '3', '4'];
  let num2 = ['5', '6', '7', '8'];
  let Concatenate = num.concat(num2)
  console.log("The new array is: ", Concatenate);
  

  Output:

  The new array is: [ '1', '2', '3', '4', '5', '6', '7', '8' ]

• Example-2

  let num = ['1', '2', '3', '4'];
  let num2 = ['5', '6', '7', '8'];
  let num3 = ['9', '10', '11', '12'];
  let Concatenate = num.concat(num2,num3)
  console.log("The new array is: ", Concatenate);
  

  Output:

  The new array is: [ '1', '2', '3', '4', '5', '6', '7', '8', '9', '10', '11', '12']

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JavaScript Array splice()

The splice() method can be used to add new items to an array:

• Example

  let num = ['1', '2', '3', '4'];
  num.splice(2,0, '2.5');
  console.log("The new array is: ", num);
  

  Output:

  The new array is: [ '1', '2', '2.5', '3', '4' ]

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JavaScript Array splice()

The splice() method can be used to add new items to an array:

• Example

  let num = ['1', '2', '3', '4'];
  num.splice(2,0, '2.5');
  console.log("The new array is: ", num);
  

  Output:

  The new array is: [ '1', '2', '2.5', '3', '4' ]

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JavaScript Array slice()

The slice() method slices out a piece of an array into a new array.

• Example

  let num = ['1', '2', '3', '4'];
  let slicing = num.slice(1);
  console.log("The new array is: ", slicing);
  

  Output:

  The new array is: [ '2', '3', '4' ]

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JavaScript Sorting Arrays

Sorting an Array

The sort() method sorts an array alphabetically:

• Example

  let num = ['c', 'b', 'a', 'd'];
  let sorting = num.sort();
  console.log("The sorted array is: ", sorting);
  

  Output:

  The sorted array is: [ 'a', 'b', 'c', 'd' ]

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Reversing an Array

The reverse() method reverses the elements in an array.

• Example

  let num = ['c', 'b', 'a', 'd'];
  let sorting = num.sort();
  let reversing = num.reverse();
  console.log("The sorted array is: ", reversing);
  

  Output:

  The sorted array is: [ 'd', 'c', 'b', 'a' ]