The Array type is used to store same type of multiple values in a single variable and further your array elements you can access using the index number.
An Array type can be defined using square brackets '[ ]' followed by elemType or generic array type 'Array
array.ts
let numberList: number[] = [1, 2, 3]; //OR let numList: Array= [1, 2, 3];
The compiled JavaScript (ES5) code for the above TypeScript code is give below:
array.js
var numberList = [1, 2, 3]; var numList = [1, 2, 3];
Tuple
The Tuple type represents a JavaScript array where you can define the datatype of each element in array.
tuple.ts
let tuple: [string, number]; tuple = ["Gurukulsight", 1];
The compiled JavaScript (ES5) code for the above TypeScript code is give below:
tuple.js
var tuple; tuple = ["Gurukulsight", 1];
Type Annotation
Type Annotations means defining the type of a variable explicitly. The type used to specify an annotation can be a primitive type, an object type or any complex structure to represent data.
The type of a variable is defined by using colon (:) followed by type.
Syntax
: = ; : ;
type_annotation.ts
let num: number = 2; //type of num is number let str: string = "Gurukulsight"; //type of str is string let numberList: number[] = [1, 2, 3]; //type of numberList is number array
The compiled JavaScript (ES5) code for the above TypeScript code is give below:
type_annotation.js
var num = 2; var str = "Gurukulsight"; var numberList = [1, 2, 3];
Type Inference
Type inference is a mechanism to determine the type of data at compile time in the absence of explicit type annotations. TypeScript will infer the type from the initial value.
type_inference.ts
let myString = 'Hello Gurukulsight'; // string let myBool = true; // boolean let myNumber = 1.23; // number let myArray = ['Hello', 'Gurukulsight']; // string[]
The compiled JavaScript (ES5) code for the above TypeScript code is give below:
type_inference.js
var myString = 'Hello Gurukulsight'; // string var myBool = true; // boolean var myNumber = 1.23; // number var myArray = ['Hello', 'Gurukulsight']; // string[]
Type Assertion
A type assertion is just like a type casting, but it doesn’t perform special type checking or restructuring of data just like other languages like C# and Java. This process entirely works on compile time. Hence it has no impact on runtime.
Type assertions can be done using two ways
1. Angle-bracket syntax
anglebracket.ts
let anyValue: any = "Welcome to www.gurukulsight.com!"; let strLength: number = (anyValue).length;
The compiled JavaScript (ES5) code for the above TypeScript code is give below:
anglebracket.js
var anyValue = "Welcome to www.gurukulsight.com!"; var strLength = anyValue.length;
2. As syntax
anglebracket.ts
let anyValue: any = "Welcome to www.gurukulsight.com!"; let strLength: number = (anyValue).length;
The compiled JavaScript (ES5) code for the above TypeScript code is give below:
anglebracket.js
var anyValue = "Welcome to www.gurukulsight.com!"; var strLength = anyValue.length;
What do you think?
I hope you will enjoy the Object and Miscellaneous Data Type in TypeScript while developing your web app. I would like to have feedback from my blog readers. Your valuable feedback, question, or comments about this article are always welcome.
Share Article
Take our free skill tests to evaluate your skill!

In less than 5 minutes, with our skill test, you can identify your knowledge gaps and strengths.