JavaScript .splice() method

There are many array methods in Javascript but the one with which I struggle the most is, .splice() method.

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So the other day, I came across a leet code problem, which asked me to manipulate an array without making a copy of it! I searched for methods and I remembered, that .splice() can be useful for this problem. So without wasting any time lets dive into the basics of .splice() method.

              Deleting A Number from an Array 
let array = [2,3,4,5,6]                                                  //At index 0, let's delete the first number which is 2 in this case!
array.splice(0, 1) 
==> return value:[2] // returns the removed element
==> console.log(array)// [3,4,5,6]
//At index 0, Let's delete, first two numbers which is 2 and 3 
array.splice(0, 2)
==>  return value:[2,3]
==>  console.log(array) // [4,5,6]

In the above example .splice() is taking two parameters:

• The index number(the point at which we want to start deleting elements)
• The second parameter is the number of elements we want to remove from an array.

                Delete elements and add things
let array = [2,3,4,5,6]
//starting from index one, I want to remove two elements and add chicken
array.splice(1,2, "chicken")
==> return value: [ 3, 4 ]
==> console.log(array) // [ 2, 'chicken', 5, 6 ]

Here we are giving .splice(), three parameters, the third parameter is optional. Recap:

1. First parameter: Starting index, the point at which you want to delete things
2. Second parameter: Number of elements, you want to remove from an array
3. Third parameter: Optional, elements you want to add at a specified position

                     Delete none, Add things 
let array = [2,3,4,5,6]
//At index one, delete nothing (hence 0 as the second parameter), and add few more elements
array.splice(1,0,"grandma", "loves", "chicken")
==> return value: []
==> console.log(array) // [ 2, 'grandma', 'loves', 'chicken', 3, 4, 5, 6 ]

When you don’t want to delete anything, just add “0”, to the second parameter.

Replace elements with other things
let array = [2,3,4,5,6]
//At index 4, replace number 6 with other elements
array.splice(4, 1,"grandma", "loves", "eric")
==> return value: [ 6 ]
==> console.log(array)// [ 2, 3, 4, 5, 'grandma', 'loves', 'eric' ]

I hope this blog was helpful! Now go ahead and play around with .splice() until it is clear and also challenge yourself with a leet code problem: Move Zeros. Here is a pdf, which includes methods available in Javascript.

Array.prototype.splice()