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TypeScript Number

Summary: In this tutorial, you’ll learn about the TypeScript number data type and how to use it to represent numeric values.

All numbers in TypeScript are either floating-point values or big integers. Floating-point numbers have the type number while big integers have the type bigint.

The number type #

The following shows how to declare a variable that holds a floating-point value:

let price: number;

Alternatively, you can initialize the price variable to a number:

let price = 9.95;

As in JavaScript, TypeScript supports the number literals for decimal, hexadecimal, binary, and octal literals:

Decimal numbers #

The following shows some decimal numbers:

let counter: number = 0;
let x: number = 100, 
    y: number = 200;

Binary Numbers #

The binary number uses a leading zero followed by a lowercase or uppercase letter “B” e.g., 0b or 0B :

let bin = 0b100;
let anotherBin: number = 0B010;

Note that the digit after 0b or 0B must be 0 or 1.

Octal Numbers #

An octal number uses a leading zero followed by the letter o (since ES2015) 0o. The digits after 0o are numbers in the range 0 through 7:

let octal: number = 0o10;

Hexadecimal numbers #

Hexadecimal numbers use a leading zero followed by a lowercase or uppercase letter X (0x or 0X). The digits after the 0x must be in the range (0123456789ABCDEF). For example:

let hexadecimal: number = 0XA;

JavaScript has the Number type (with the letter N in uppercase) that refers to the non-primitive boxed object. You should not use this Number type as much as possible in TypeScript.

Big Integers #

The big integers represent whole numbers larger than 253 – 1. A bigint literal has the n character at the end of an integer literal like this:

let big: bigint = 9007199254740991n;

Summary #

  • All numbers in TypeScript are either floating-point values that get the number type or big integers that get the bigint type.
  • Avoid using the Number type as much as possible.

Quiz #

Quiz

TypeScript Number Type

4 questions

Review the lesson learning objectives

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