There are many ways to append one array to another in JavaScript. In the article, I will show you some ways to go through some of the built-in JavaScript functions or methods so that you can understand and implement them. I have used some of the most concise and easy-to-understand examples.
How did I append one array to another in JavaScript?
Using the loop For and push() method
When working with arrays, we often use loops in which the For loop is used the most, so to append one array to another in Javascript, we can also use the For loop to perform.
Before I do, I will help you understand how the push() method of arrays works and how to do it.
Syntax
array.push(item1, item2, ..., itemX)
Parameter
- item1, item2, …, itemX: These are the elements you want to add to your array
Here I will implement using For loop and push() method to add two strings as follows:
const nums1 = [3, 4, 6, 8]; const nums2 = [1, 2, 9, 5, 7]; // Using For loop and push() method for (let index = 0; index < nums2.length; index++) { nums1.push(nums2[index]); } console.log(nums1);
Output:
(9) [3, 4, 6, 8, 1, 2, 9, 5, 7]
I append the array ‘nums2’ to the string ‘nums1’ by traversing the elements of ‘nums2’ using a For loop and then passed them to the push() method to add each element of ‘nums2’ to ‘nums1’ ‘.
Using spread(…) operator
spread(…) operator expands an iterable into more elements. We can use it to concatenate two arrays combined with the push() method or without any method. It can also append one array to another okay.
When spread(…) operator combined with push() method we will do the following:
const nums1 = [3, 4, 6, 8]; const nums2 = [1, 2, 9, 5, 7]; // Using spread(...) operator and push() method nums1.push(...nums2); console.log(nums1);
Output:
(9) [3, 4, 6, 8, 1, 2, 9, 5, 7]
Or we can use it without any other methods like this:
const nums1 = [3, 4, 6, 8]; const nums2 = [1, 2, 9, 5, 7]; // Using spread(...) operator const nums = [...nums1, ...nums2]; console.log(nums);
Output:
(9) [3, 4, 6, 8, 1, 2, 9, 5, 7]
We have many ways to use the spread(…) operator to concatenate two arrays, and both achieve the results we expect.
Using the concat() method
concat() method is a built-in method to concatenate two arrays by simply passing the array you want to concatenate as its parameter.
Syntax
array1.concat(array2, array3, ..., arrayX)
Parameter
- array2, array3, …, arrayX: One or more arrays you want to concatenate.
Example:
const nums1 = [3, 4, 6, 8]; const nums2 = [1, 2, 9, 5, 7]; // Using the concat() method const nums = nums1.concat(nums2, [0, 10, 11]); console.log(nums);
Output:
(12) [3, 4, 6, 8, 1, 2, 9, 5, 7, 0, 10, 11]
With the concat() method, we can combine multiple strings in just a few quick and easy steps.
Summary
Above are some common ways when we want to append one array to another in JavaScript. When we use the concat() method, the string concatenation is no longer a problem. In return, it is straightforward and faster. I hope the article helps you and your program. Good luck.
Maybe you are interested:
- Sort an Array of Objects by Date property in JavaScript
- Get the First and Last Elements of an Array in JavaScript
- Remove Empty Objects from an Array in JavaScript

My name is Tom Joseph, and I work as a software engineer. I enjoy programming and passing on my experience. C, C++, JAVA, and Python are my strong programming languages that I can share with everyone. In addition, I have also developed projects using Javascript, html, css.
Job: Developer
Name of the university: UTC
Programming Languages: C, C++, Javascript, JAVA, python, html, css