Javascript Grammar

- What is it called in Korean?
- Use  _______  to change the value.

- What is it called in Korean?
- Creating this is like assigning _______ to a value.
- Variable makes the assigned value _______ & _______.

- What is it called in Korean?
- It indicates the _______ of an assigned variable.
- (a),(b),(c) and (d) can be used to create an identifier.
- Identifiers cannot start with _______.
- Javascript _______ cannot be used as an identifer.

- Use _______case.
- What is _______case?

- List 7 types of values in Javascript. 
  *hint: use the acronym 'bonus'*
- Use _______ operator to find the type of a value. --- #### Number
- Number._______(1); // ? Number._______(0.1); // ?
- What is the property of Number object that checks if a 
  number is a integer and returns boolean?

arithmetic operators
- 14 % 3; // ? 
- What is the name of % ?
- 4 ** 3 // ? 
- What is the nmae of ** ?

comparison operators
- What is the difference between == and === ?
- 0 == false // ?
- 0 === false // ?
- 2 == '2' // ?
- 2 === '2' // ?
- == is known as t_______ c_______ operator
- === is known as s_______ e_______ operator
- one shouuld always use _______ operator for comparing 
  variables or just for any comparison
- null == undefined // ?
- null === undefined // ?
- NaN === NaN // ?
- Remember that NaN is _______ _______ _______ _______,
 including _______.

increment/decrement operators
- What is the difference between --a and a-- (or ++a and a++)?
- Both increments/decrements the variable. 
  However, returns different values.
- When a = 1, ++a returns _______.
- When a = 1, a++ returns _______.
- Think in terms of the order of the operator & value.
- In any case, follow the guideline "prefer ++a over a++".

assignment operators 
- +=, -=, *=, /=, %=, **=

- associativity 
- left associativity = _______ to _______.
- right associativity = _______ to _______.

example of right associativity: the assignment operators
- a = b = 5 // order of assignment ?

- Which operator has a higher operator precedence? && or ||?

- _______, _______, _______, _______.

- What does it stand for?
- What type is NaN?
- NaN === NaN; // ?
- 0 / 0; // ?
- 1 * 'hello'; // ?

- parseInt('123'); // ?
- parseInt('110',2); // ?
- parseFloat('12.345'); // ?
- parseInt('hello'); // ?

- What does parseInt() & parseFloat() do?

- What are the three different ways of writing strings?
- What is the name of ` ` and its function?

- 'a' < 'b'; // ?
- 'abc' > 'aaa'; // ?
- 'a' , 'z'; // ?
- '한글' < '한국어'; // ?
- '2' < '10'; // ?

- 'hello'[3] // ?
- 'hello'.concat('fun','javascript'); // ?
- '6'.repeat(3); // ?
- 'hello javascript'.includes('hello'); // ?
- 'hello javascript'.startsWith('he'); // ?
- 'hello javascript'.endsWith('ript'); // ?
- 'hello javascript'.indexOf('java'); // ?
- 'hello'.slice(2,4); // ?
- '    hello    '.trim(); // ?
- 'hello!fun!javascript'.split(!); // ?

var a = 'hello';
a[3] = '0';
console.log(a); // ?

- The only boolean values are _______ and _______.

- !!'hi'; // ?
- Boolean('hi'); // ?

- In Javascript, all values are truthy but for these 8 values:
  *hint: 3 number types 2 string types 1 boolean type + 2 more.* --- #### null & undefined
- What are their differences?
- As a programmar one should use _______ in order to indicate
  that the value does not exist.

- typeof null; // ? *hint: not null type* ---  #### Function
function add(x,y){return x+y;}
             (a)   (b)
- What is (a)? and what is it called in Korean?
- What are the two main functions of (b)?  

function foo(x,y){
    console.log(arguments);
}
foo(1,2); // ? *hint: [object Arguments]{   ?   }*

- can use arguments.length
- however, object.length returns undefined => instead use
  Object.keys(myObj).length
- This is because arguments keyword has its own property 
  called length, but object does not. ---  #### Control flow
function add(x,y){ return function bar(){}; }

- add() || 3 // ?
- add()() || 3 // ?

- What are the 4 keywords when using switch? 
- write an example of using switch.

- What are their functions in association with a loop?
  break: ex_______ loop, moves to next code.
  continue: sk_______ the rest oft he code in the loop.

for( init() ; isValid() ; console.log(3) ) { return 3; }

- Write the order of each expression executed from the for
  loop above. ---  #### Objects

- What are these and what is the specific case bracket 
  notation must be used?

var person;

//Adding
person.name = 'Imho Jang'
person.age = '25';
person.languages = ['Korean','English'];

//Writing
person.age = '26';

//Reading
person.name; // ?
perosn.age; // ?

//Deleting
delete person.name;

//Checking
'name' in person; // ?
'phone number' in person; // ?

- A function can be assigned as the value of a property
  in an object. This is called a method.
- Write a sample method. --- #### Array
- typeof []; // ?
- A main difference between object and array is that 
  items in array has an _______.
- Each value in an array are called _______ or _______. 
  What is it in Korean?

- What is it called in Korean? 값
- Use OPEARTOR to change the value.

- What is it called in Korean? 변수
- Creating this is like assigning NAME to a value.
- Variable makes the assigned value USABLE & REUSABLE.

- What is it called in Korean? 식별자
- It indicates the NAME of an assigned variable.
- ALPHABET, NUMBER, DOLLAR SIGN $ and UNDERSCORE _ can be 
  used to create an identifier.
- Identifiers cannot start with NUMBER.
- Javascript KEYWORDS cannot be used as an identifer.

- Use CAMELcase.
- What is CAMELcase? -> cookiesAndCream; icedAmericano, bakedPotato

- List 7 types of values in Javascript.  
  *hint: use the acronym 'bonus'*
  BOOLEAN OBJECT NUMBER NULL UNDEFINED STRING SYMBOL
- Use 'typeof' operator to find the type of a value. --- #### Number
- Number.IsIntegre(1); // ? Number.IsInteger(0.1); // ?

arithmetic operators
- 14 % 3; // ? 2 
- What is the name of % ? MOD OPERATOR
- 4 ** 3 // ? 4*4*4 = 64
- What is the nmae of ** ? EXPONENTIATION OPERATOR

comparison operators
- What is the difference between == and === ? == IS FLEXIBLE
  IN CHECKING EQUALITY WHILE === IS STRICT
- 0 == false // ? TRUE
- 0 === false // ? FALSE
- 2 == '2' // ? TRUE
- 2 === '2' // ? FALSE
- == is known as tYPE cOERCION operator
- === is known as sTRICT eQUALITY operator
- one shouuld always use STRICT EQUALITY operator for comparing
  variables or just for any comparison
- null == undefined // TRUE
- null === undefined // FALSE
- NaN === NaN // FALSE
- Remember that NaN is NOT EQUAL TO ANYTHING, including ITSELF.

increment/decrement operators
- What is the difference between --a and a-- (or ++a and a++)?
  THEY ARE DIFFERENT IN TERMS OF RETURN VALUES. 
- Both increments/decrements the variable. However, returns 
  different values.
- When a = 1, ++a returns 2.
- When a = 1, a++ returns 1.
- Think in terms of the order of the operator & value.
- In any case, follow the guideline "prefer ++a over a++".

assignment operators 
- +=, -=, *=, /=, %=, **=

- associativity 
- left associativity = LEFT to RIGHT.
- right associativity = RIGHT to LEFT.

example of right associativity: the assignment operators
- a = b = 5 // order of assignment ? (1) b = 5 (2) a = b 

- Which operator has a higher operator precedence? && or ||? &&

- NaN, -0, -infinity, +infinity

- What does it stand for? NOT A NUMBER
- What type is NaN? NUMBER
- NaN === NaN; // FALSE
- 0 / 0; // ? NaN
- 1 * 'hello'; // ? NaN

- parseInt('123'); // 123
- parseInt('110', 2); // 6 -> parses integer into binary number
- parseFloat('12.345'); // 12.345
- parseInt('hello'); // NaN

- What does parseInt() & parseFloat() do? PARSES A NUMBER IN 
  STRING INTO INTEGER OR DECIMAL

- What are the three different ways of writing strings? ``, '', and ""
- What is the name of ` ` and its function? TEMPLATE LITERAL

- 'a' < 'b'; // TRUE
- 'abc' > 'aaa'; // TRUE
- 'a' > 'z'; // FALSE
- '한글' < '한국어'; // FALSE
- '2' < '10'; // FALSE

- 'hello'[3] // ? 'l'
- 'hello'.concat('fun','javascript'); // 'fun javsacript'
- '6'.repeat(3); // ? '666'
- 'hello javascript'.includes('hello'); // ? TRUE
- 'hello javascript'.startsWith('he'); // ? TRUE
- 'hello javascript'.endsWith('ript'); // ? TRUE
- 'hello javascript'.indexOf('java'); // ? 6
- 'hello'.slice(2,4); // ? 'll'
- '    hello    '.trim(); // ? 'hello'
- 'hello!fun!javascript'.split(!); // ? ['hello', 'fun', 'javascript'];

var a = 'hello';
a[3] = '0';
console.log(a); // 'hello'

- The only boolean values are TRUE and FALSE.

- !!'hi'; // ? TRUE
- Boolean('hi'); // ? TRUE

- In Javascript, all values are truthy but for these 8 values:
  *hint: 3 number types 2 string types 1 boolean type + 2 more.*
  (1) false, (2) NaN, (3) -0, (4) 0, (5) null, (6) undefined, (7) '', (8) "", 

- What are their differences? 
UNDEFINED IS USED TO INDICATE THAT A VALUE HAS NEVER BEEN ASSIGNED.
NULL IS USED TO INDICATE THAT A VALUE DOES NOT EXIST.
- As a programmar one should use NULL in order to indicate that 
  the value does not exist.

- typeof null; // ? OBJECT *hint: not null type*

function add(x,y){return x+y;}
             (a)   (b)
- What is (a)? ARGUMENT and what is it called in Korean? 인자
- What are the two main functions of (b)? IT IS THE CONCLUDING VALUE ON EXECUTION  
  OF THE FUNCTION AND IT ALSO TERMINATES THE FUNCTION. CODE BELOW RETURN LINE  
  INSIDE THE FUNCTION BODY WILL NOT BE READ.

function foo(x,y){
    console.log(arguments);
}
foo(1,2); // ? *hint: [object Arguments]{ 0: 1, 1: 2  }*

- can use arguments.length
- however, object.length returns undefined => instead use Object.keys(myObj).length
- This is because arguments keyword has its own property called length, but object does not.

function add(x,y){ return function bar(){}; }

- add() || 3 // function bar()
- add()() || 3 // 3

- What are the 4 keywords when using switch? default, case, switch, break
- write an example of using switch.

function translateColor(english) {
  var result;
  switch (english) {
    case 'red':
    result = '빨강색';
    break;
    case 'blue':
    result = '파랑색';
    break;
    case 'purple':
    result = '보라색';
    break;
    case 'violet':
    result = '보라색';
    break;
    default:
    result = '일치하는 색깔이 없습니다.';
  }
  return result;
}

- What are their functions in association with a loop?
  break: exITS loop, moves to next code.
  continue: skIPS the rest oft he code in the loop.

for( init() ; isValid() ; console.log(3) ) { return 3; }

- Write the order of each expression executed from the for loop above. 
  (1) init(), (2) isValid(), (3) return 3, (4) console.log(3)

- What are these and what is the specific case bracket notation must be used? 
WHEN THE PROPERTY NAME INCLUDES STRINGS THAT DOES NOT FOLLOW THE RULES USED
TO CREATE IDENTIFIERS (ex) Strings that are not alphabet, number, $, or _.

var person;

//Adding
person.name = 'Imho Jang'
person.age = '25';
person.languages = ['Korean','English'];

//Writing
person.age = '26';

//Reading
person.name; // 'Imho Jang'
perosn.age; // '25'

//Deleting
delete person.name;

//Checking
'name' in person; // TRUE
'phone number' in person; // FALSE

- A function can be assigned as the value of a property in an object. This is called a method.
- Write a sample method.
var person = {  
  greet: function() {
    return 'hello';  
  }
};
 
person.greet(); // 'hello';

- typeof []; // object
- A main difference between object and array is that items in array has an ORDER.
- Each value in an array are called ITEM or ELEMENT. What is it in Korean? 항목 또는 요소