JavaScript Study Note

Variable name conventions

// let $function =27;
// let FirstName = “Jonas”;
// let PI = 3.1415;
// let myFirstJob =’Programming’;
// let myCurrentJob=’Teacher’;
// let job1=’programmer’;
// let ojb2 = ‘teacher’;

Data Type

let javascriptIsFun = true;
console.log(javascriptIsFun)
console.log(typeof true)-boolean
console.log(typeof javascriptIsFun)-boolean
console.log(typeof 23)- number
console.log(typeof ‘Jonas’)-string
javascriptIsFun=”Yes” 
console.log(typeof javascriptIsFun)
let year;
console.log(year)
console.log(typeof year)
year=1994;
console.log(year)
console.log(typeof year)
console.log(typeof null)- It show as object on Console, but actualy undefiend