Javascript is a high-level object-oriented, multi-paradigm programming language.
- programming language: instruct computer to do things
- object-oriented: based on objects for storing most kinds of data
- multi-paradigm: we can use different styles of programming
- high-level: we dont have to worry about complex stuff like memory management.
40+2+32
why is this result not showing in console?
- because the console is just the environment that was build to execute small pieces of code and then show result imediately. It does not show operation in code by default. So we have to use console.log(40+2+32);
Data Type:
1. number: floating point numbers
2. string: sequence of characters
3. boolean: logical type that can only be true or false
4. undefined: value taken by a variable that is not yet defined
5. null: also mean empty value
6. symbol(ES2015): value that is unique and cannot be changed
7. bigInt(ES2020): larger integers than the number type can hold
const - it creates variable that cannot be assigned/ immutable variable
const birthyear = 1990 birthyear cannot be change only the ages.
console.log(firstName+ ' '+lastName)
map() 메서드는 배열 내의 모든 요소 각각에 대하여 주어진 함수를 호출한 결과를 모아 새로운 배열을 반환합니다
map method - loop over array/ make brand new array
filter method - filter for original array new filtered array.
promise : an object that is used as a placeholder for the future result of an asynchronous operation.
