Copy/Clone an Array or Object in JavaScript The Right Way [Examples]

How to Copy/Clone JavaScript Array

This tutorial will show you how to properly copy/clone an array or object in JavaScript – it’s not as simple as it seems! Copying an array or object may seem simple – but JavaScript throws a spanner in the works – the fact that when you assign the value of one variable to another it references the original variable. This means that if the value of the original variable is changed, the value of the copy will change too! To get around this, you will need to clone the array – ensuring … Read more

How to Convert an Object to an Array in JavaScript [Examples]

JavaScript Convert Object to Array

This article will show you the ways to convert an object to an array in JavaScript – quickly and easily. There are many ways to convert objects to arrays, but these (should) be the most straightforward methods. Converting Object to Array in JavaScript – Values Only If you only need the values from the object, the Object.values() method will extract them into an array: var myObject = { colour: ‘blue’, number: 43, name: ‘Fred’, enabled: true }; var values = Object.values(myObject); console.log(values); The above will return an array with … Read more

Converting Object to an Array Recursively in JavaScript

JavaScript Recursive Object to Array

The Object.entries() method in JavaScript can be used to convert an object to an array – but it doesn’t work recursively. So here’s a function to accomplish that. I can’t think of a reason why you’d want to do this, but it came up while putting together an article on using Object.entries() – so here it is! Recursive Function for Converting Objects to Arrays I’ll let the comments do the talking as to what’s going on. The gist of it is that (for whatever reason) you want to convert an … Read more

What is the ‘this’ Keyword in JavaScript (Object-Oriented Programming)

JavaScript 'this'

The ‘this‘ keyword in JavaScript is a confusing concept for some – the meaning of ‘this‘ changes based on context.  This article explains what ‘this‘ is. What is Object-Oriented Programming Object-Oriented Programming is a way of structuring your code so that data is organized into objects. JavaScript supports Object-Oriented programming and provides various tools to help implement it. Put simply, rather than having a bunch of separate abstract variables describing an item, you combine them into a single object which represents that item. You can also add functions … Read more

JavaScript for Loops – How to Use Them [Examples]

How to use for loops in JavaScript

This article will show you how to use the simplest JavaScript loop – the for loop, and provide code examples. JavaScript for Loops JavaScript’s for loops are used to execute a block of code repeatedly until a condition is met. The initial variables, condition that must be met, and the expression which progresses the loop are all defined within the loop expression. for loop Syntax JavaScript for loops follow the following syntax: for (INITIALIZATION; CONDITION; FINAL_EXPRESSION) { //Code to be executed in the loop } Note that: INITIALIZATION sets the variable which is used to control … Read more

How to Use Nested For Loops in JavaScript, with Examples

JavaScript nested for loops

This article will quickly explain nested for loops in JavaScript, how they are used with multidimensional arrays, and show some examples. For Loops We’ve already covered for loops – check out our article here. To sum up the article, for loops repeat a block of code for a given number of iterations: for (let i = 0; i <= 3; i++) { console.log(i); // Will output the numbers 0-3 to the console } Above, a for loop is defined that defines an initial variable i that is used to control the loop, sets a … Read more

Filter JavaScript Array With Multiple Conditions/Values [Examples]

JavaScript filter array using multiple conditions/values

This article will show you how to filter an array using multiple conditions, to return multiple values. Example code is provided. We’ve already covered filtering arrays in general – this article covers specifically how multiple conditions can be used with the Array.filter() method. The Array.filter() Method The filter() method is available on all arrays in JavaScript. It creates a new array, containing only the items from the original array which passes all conditions in a provided function. filter() Method Syntax The syntax for the array filter() method is as follows: ARRAY.filter(ELEMENT => FUNCTION) Note that: ARRAY is … Read more

The JavaScript valueOf() Method – What Does it Actually Do?

JavaScript valueOf()

This quick tutorial will explain the JavaScript valueOf() Method, what it does, and why you might use it. The JavaScript valueOf() method gets the primitive value of the object it is called from. Usually you will not need to call it, however it does have its use cases. Primitives vs Objects In JavaScript, a value or variable has a type of value. A primitive is a value that is not an object, with no methods or properties, representing only the data that it exists as. JavaScript has 7 primitive data types: string number bigint boolean undefined … Read more

Check/Validate String Matches Regex in JavaScript [Examples]

JavaScript regex match

This article will show you how to use Regular Expressions (Regex) to validate matching strings in JavaScript. All user input collected in your applications should be validated. If an email address is required, a valid email address should be entered, or sending the email will fail. If a phone number is required, a valid phone number must be entered, and so on. Regex can be used for this validation by matching a whole string to a specified format. Regex can also be used to search … Read more

for…in Loops in JavaScript – How to Use Them

JavaScript loop

The for…in loop in JavaScript loops over all of the properties in an object. This article will explain why and how to use it. JavaScript Objects JavaScript objects are a kind of variable which store the properties for an item you are representing in your code. For example, you may have a car object, which of which the make, year, model, and colour of a car are it’s properties. Each car object would have it’s own separate list of properties which define that car. JavaScript objects can also be used as hash tables – providing … Read more