Udemy 유데미 The Web Developer Bootcamp Section 14~15 JavaScript Basics

유데미 웹개발 부트캠프 섹션 14~15

• 크롬에서 console 여는 단축키: option + commd + J
• R E P L : Read Evaluate Print Loop

• NaN : Not a Number
  • a numeric value that represents sth that is not a number....
  • 0/0 --> NaN
  • 1+NaN --> NaN
•  const: 한번 정한 값을 바꿀수없음 constant variable임
• var: old way of making variables
• Boolean: True or False
• .trim(): space 부분 없애줌
• toLowerCase()
• toUpperCase()
• convention naming: 첫단어는 lowercase; ex) highScore
• indexOf() : The indexOf() method, given one argument: a substring to search for, searches the entire calling string, and returns the index of the first occurrence of the specified substring. Given a second argument: a number, the method returns the first occurrence of the specified substring at an index greater than or equal to the specified number.
• .slice(): 잘라서 새로운 string을 만듬
• .replace():
  • .replace('a', 'b') 맨 처음 a 문자만를 대체함
  • .replaceAll(): 모든 해당 문자를 대체함 -> 쓸수있는 브라우저는 제한적
• .repeat(n): n번 반복

String Template Literals

• template literals are strings that allow embedded expressions, which will be evaluated and then turned into a resulting string
  • `I counted ${3+4} sheep`
    • back-ticks `` 사용 (tab 키 윗키)
    • ${....} 

 

Undefined & Null

• Null: international absence of any value
  • must be assigned
  • value is explicitly nothing
• Undefined
  • Variables that do not have an assigned value

 

Math Object

• contains properties and methods for mathematical constants and functions
• Math.floor() : 올림
• Math.ceil(): 내림
• Math.random(): 랜덤 숫자를 생성
• random integers 생성하는 법

how to create random integer