{"id":14187,"date":"2022-11-17T05:31:58","date_gmt":"2022-11-17T11:31:58","guid":{"rendered":"https:\/\/upmostly.com\/?p=14187"},"modified":"2022-11-17T05:31:59","modified_gmt":"2022-11-17T11:31:59","slug":"primitive-types-in-typescript","status":"publish","type":"post","link":"http:\/\/upmostly.com\/typescript\/primitive-types-in-typescript","title":{"rendered":"Primitive Types in TypeScript"},"content":{"rendered":"\n

TypeScript<\/a> provides some useful primitive types that you’ll be using every day. In this article, I’ll explain them, what they’re for, and the TypeScript-specific primitives.<\/p>\n\n\n\n

number<\/h2>\n\n\n\n

The number type works as you expect in TypeScript, covering all the ways JavaScript allows you to represent a number:<\/p>\n\n\n\n

let n: number;\nn = 3; \/\/Integer\nn = 3.14; \/\/Floating point\nn = 3.14e2; \/\/exponent\nn = 0b0011; \/\/Binary\nn = 0xc0ff33; \/\/Hexadecimal\nn = 0o1066; \/\/Octal\nn = 22 \/ 7;<\/code><\/pre>\n\n\n\n
You can also easily convert a number to a string in TypeScript, using the .toString() method of the number:<\/p>\n\n\n\n
const myString: string = n.toString();<\/code><\/pre>\n\n\n\n
A cool feature of this function is that it accepts a number as the radix\/base, so you can easily convert a number to a binary string, hexadecimal, or any other base up to 26.<\/p>\n\n\n\n
<\/p>\n\n\n\n
string<\/h2>\n\n\n\n
The string type also acts as it does in JavaScript, storing text values.<\/p>\n\n\n\n
let s: string;\ns = 'Hi from Upweekly!';<\/code><\/pre>\n\n\n\n
Strings are also very useful when you combine them with type literals and type unions, letting you define a type as “only one of these possible strings”:<\/p>\n\n\n\n
type AlertLevel = 'info' | 'warning' | 'critical';\n\nfunction alert(level: AlertLevel, message: string) {}\n\nalert('info', 'Rebooting the Upmostly quantum mainframe'); \/\/\u2705\nalert('hi', 'This doesnt work'); \/\/\u274e TS2345: Argument of type '\"hi\"' is not assignable to parameter of type 'AlertLevel'.<\/code><\/pre>\n\n\n\n
You can convert most types, e.g. numbers, and objects to a string by seeing if they have a .toString() method. You can convert a string to a number using the Number.<\/p>\n\n\n\n
const myNumber = 3.141;\n\nconst myString: string = myNumber.toString();\n\nconst backToNumber: number = Number.parseFloat(myString); \/\/3.141\nconst toInteger: number = Number.parseInt(myString); \/\/3<\/code><\/pre>\n\n\n\n
parseInt() also accepts a base as a parameter, letting you convert things like binary and hexadecimal numbers to strings.<\/p>\n\n\n\n
boolean<\/h2>\n\n\n\n
Booleans, very simply store true or false values. One pitfall you might run into is converting your boolean to a string. The easiest way to convert these to a string is using a ternary operator:<\/p>\n\n\n\n
const bool: boolean = true;\n\nconst boolToString = bool ? 'true' : 'false';<\/code><\/pre>\n\n\n\n
You can of course pick your own representations for the strings.<\/p>\n\n\n\n
BigInt<\/h2>\n\n\n\n
BigInts can be used to store numbers too large to be stored in the number primitive, anything bigger than Number.MAX_SAFE_INTEGER.<\/p>\n\n\n\n
You can define a bigint by adding an “n” onto the end of your number, or by using the BigInt() constructor:<\/p>\n\n\n\n
let myBigInt = 9007199254740992n;\nlet myBigInt2 = BigInt(9007199254740992);<\/code><\/pre>\n\n\n\n
The key differences you might deal with when working with Bigint values are:<\/p>\n\n\n\n