How to declare an empty array in TypeScript
October 27, 2023
In TypeScript, declaring an empty array is a common task when developing applications. Having specific types ensures that your arrays maintain consistent data and reduces runtime errors. This guide will walk you through different ways to declare an empty array in TypeScript.
Declaring a basic empty array
The simplest way to declare an empty array in TypeScript is:
This approach declares an array named
myArray that can hold any type of value.
Strongly typed arrays
To ensure type safety, you can declare an array with a specific type. Here's how you can declare an empty array of numbers:
Similarly, for strings:
Using the Array generic type
Another method to declare an empty array with type safety is by using the Array generic type:
And for strings:
Declaring arrays of custom types
If you have custom types, like interfaces or classes, you can also declare an empty array for them. Given an interface
You can declare an empty array of
Person like this:
Or using the Array generic type:
Using tuple types
Tuple types allow you to declare an array where the type of a fixed number of elements is known but does not have to be the same. If you need an array that will always have a string and then a number, you can declare it like this:
Keep in mind that while this initializes the tuple with values, they are essentially placeholders, and you can later overwrite them.
Declaring empty arrays in TypeScript is straightforward once you know the type you want to work with. Using strongly typed arrays ensures that your code remains type-safe, preventing unexpected runtime errors. Remember to choose the method that best fits your needs and the readability of your code.
How to fix the "not all code paths return a value" issue in TypeScript
Working with WebSockets in Node.js using TypeScript
Type Annotations Can Only Be Used in TypeScript Files
Guide to TypeScript Recursive Type
How to Configure Knex.js with TypeScript