As a beginner, I also face difficulty in remembering all the functions associated with a particular topic. So I thought of writing about some important and widely used array functions in javascript which I personally feel are very useful and a must know for beginners. However, one should have at least a basic idea of all the functions.

1. Filter()

The Filter() method creates a new array filled with elements that pass a test provided by a function. However it does not change the original array.
For example,

const numbers = [32, 33, 16, 40];
const result = numbers.filter(checkNumber);

function checkNumber(number) {
  return number >= 30;
}

The filter will return [32,33,44] as these elements are greater than 30.

2. forEach()

The forEach() method calls a function for each elements in an array. It's somewhat similar to the for loop for all elements.
For example,

let text = "";
const numbers = [1,2,3,4]
numbers.forEach(functionMe);
document.getElementById("para").innerHTML = text;
function functionMe(item, index) {
  text += (index+1) + ": " + item + "<br>"; 
}

The output comes to be

1: 1
2: 2
3: 3
4: 4

3. map()

The map() method creates a new array from the results of calling a function for every element.
For example,

const numbers = [1, 4, 9, 16, 25];
document.getElementById("para").innerHTML = numbers.map(Math.sqrt);

It will display the square root of every element.

1,2,3,4,5 

4. Splice()

Splice() method overwrites the original array by adding or removing elements.
for example,

const avengers = ["Captain America", "Iron Man", "Hulk", "Thor"];

fruits.splice(3, 0, "spider man", "Dr. Strange");
// here 3 signifies index, 0 signifies that no element is to be deleted .
//If we wish to delete some elements ,then index and number of elements to be deleted should be provided.

document.getElementById("para").innerHTML = fruits;

this will add 2 elements at the index 3.

Hope this helps some peeps new to coding and web development.
For more detailed explanation of these topics you may follow this playlist [(https://www.youtube.com/playlist?list=PLgBH1CvjOA62PBFIDq55-S6Beivje30A2)]