Number type behavior in Typescript

Introduction

Numbers are used to do math and count things in programs. Understanding how numbers work helps you avoid mistakes.

When you want to add, subtract, multiply, or divide values.

When you need to compare two numbers to see which is bigger.

When you want to store prices, ages, or scores.

When you want to check if a number is whole or has decimals.

When you want to convert strings to numbers for calculations.

Syntax

Typescript

let myNumber: number = 42;

// You can do math like:
let sum = myNumber + 8;
let division = myNumber / 2;

TypeScript uses the number type for all numbers, including decimals.

Numbers can be integers (whole) or floating-point (decimals).

Examples

Store whole numbers and decimal numbers using number type.

Typescript

let age: number = 30;
let price: number = 19.99;

Division can produce decimal numbers.

Typescript

let result = 10 / 4; // result is 2.5

You can use scientific notation for big or small numbers.

Typescript

let bigNumber = 1e6; // 1 million

Check if a number is whole using Number.isInteger().

Typescript

let isInteger = Number.isInteger(5); // true
let isInteger2 = Number.isInteger(5.5); // false

Sample Program

This program shows basic math operations and checks if numbers are integers. It also shows a big number using scientific notation.

Typescript

let a: number = 10;
let b: number = 3;

console.log(`a + b = ${a + b}`);
console.log(`a - b = ${a - b}`);
console.log(`a * b = ${a * b}`);
console.log(`a / b = ${a / b}`);

console.log(`Is a integer? ${Number.isInteger(a)}`);
console.log(`Is b integer? ${Number.isInteger(b)}`);

let bigNum: number = 1e4;
console.log(`Big number: ${bigNum}`);

Important Notes

All numbers in TypeScript are floating-point, so be careful with very precise decimal math.

Use Number.isInteger() to check if a number has no decimals.

Be aware that dividing by zero gives Infinity or -Infinity, not an error.

Summary

TypeScript uses one number type for all numbers.

Numbers can be whole or decimal, and you can do math with them easily.

Use built-in functions like Number.isInteger() to check number properties.