Osama

Posted on Apr 24, 2022

Javascript 1O1 series: Array’s Methods And Iterators Part(1), Methods.

#javascript #programming #tutorial #webdev

You'll learn:

Some useful array methods to make dealing with arrays is an easy thing, I hope you won't find any issues with handling arrays operations from now on.

Insert and Remove:

shift:
shift() is used to remove the first element of the array.
Array.shift()

unshift:
unshift is used to insert an element into the array, unshift will add the element to the start of the array

push:
push is used to append elements to the array, (add to the end)

pop:
pop is used to pop out (remove) the last element of the array

Sub-arrays:

slice:
slice is used to copy elements in a specific range.
e.g.you have an array and you want to get the elements between index 1 and index 3

when the end parameter is not defined, then the slice extends to the end of the array

let slicedArr2 = arr.slice(1) // [2,3,4,5,6,7,8,9]

spliced:
slice is used to REMOVE elements from an array.

Reordering:

reverse:
used to reverse the array's elements.

sort:

By default, the sort() function sorts values as strings.
This works well for strings ("Apple" comes before "Banana").
However, if numbers are sorted as strings, "25" is bigger than "100", because "2" is bigger than "1".
Because of this, the sort() method will produce incorrect result when sorting numbers.
You can fix this by providing a compare function.

so without compare function, sort() is not that useful.
more about sort:

Array.prototype.sort() - JavaScript | MDN

The sort() method sorts the elements of an array in place and returns the sorted array. The default sort order is ascending, built upon converting the elements into strings, then comparing their sequences of UTF-16 code units values.

developer.mozilla.org

Search and Sort:

includes:
used to check if an element does exist or not.

at:
simple, you pass an index and you get the value in that index.

indexOf:
indexOf() is the opposite of at(), you pass a value and get the value's index in the array.

sort:
sort can be used here as well

By default, the sort() function sorts values as strings.
This works well for strings ("Apple" comes before "Banana").
However, if numbers are sorted as strings, "25" is bigger than "100", because "2" is bigger than "1".
Because of this, the sort() method will produce incorrect result when sorting numbers.
You can fix this by providing a compare function.

so without compare function, sort() is not that useful.
more about sort:

Array.prototype.sort() - JavaScript | MDN

developer.mozilla.org

Adding and combining arrays :

concat:
used to combine (add together) two or more arrays, non of the combined arrays will be modified, concat() will return a new array instead.

Array to String conversion:

toString:
used to represent an array in string format.

there is also toLocalString(), search about it as an exercise and learn the difference between toString() and toLocalString(), if you know, please share the answer in a comment.

Other methods:

flat:
when you have a nested arrays and want to pull out all these nested arrays to a new array, flat() is used.
flat() doesn't modify the array, it returns a new array instead.

fill:
used to fill the whole or part of the array with a specific value.

References:

javascript.plainenglish.io

JavaScript: The Definitive Guide, 7th Edition [Book]

JavaScript is the programming language of the web and is used by more software developers today than any other programming language. For nearly 25 years this best seller has been … - Selection from JavaScript: The Definitive Guide, 7th Edition [Book]

oreilly.com