check data type in js
typeof("string"); //string
typeof(123); //numbercheck data type in js
typeof("string"); //string
typeof(123); //numbercustom types in typescript
// simple type
type Websites = 'www.google.com' | 'reddit.com';
let mySite: Websites = 'www.google.com' //pass
//or
let mySite: Website = 'www.yahoo.com' //error
// the above line will show error because Website type will only accept 2 strings either 'www.google.com' or 'reddit.com'.
// another example.
type Details = { id: number, name: string, age: number };
let student: Details = { id: 803, name: 'Max', age: 13 }; // pass
//or
let student: Details = { id: 803, name: 'Max', age: 13, address: 'Delhi' } // error
// the above line will show error because 'address' property is not assignable for Details type variables.
//or
let student: Details = { id: 803, name: 'Max', age: '13' }; // error
// the above line will show error because string value can't be assign to the age value, only numbers.javascript check type of variable var
> typeof "foo"
"string"
> typeof true
"boolean"
> typeof 42
"number"Copyright © 2021 Codeinu
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