Learn React with TypeScript 3

Arrays

Arrays are structures that TypeScript inherits from JavaScript. We add type annotations to arrays as usual, but with square brackets at the end to denote that this is an array type.

Let's take a look at an example:

1. Let's declare the following array of numbers in the TypeScript playground:

const numbers: number[] = [];

Here, we have initialized the array as empty.

2. We can add an item to the array by using the array's push function. Let's add the number 1 to our array:

numbers.push(1);

We used const to declare the numbers variable and was able to change its array elements later in the program. The array reference hasn't changed – just the elements within it. So, this is fine with the TypeScript compiler.

3. If we add an element with ...