1. Quick_Start.md

Basic grammer

1. automatically add ; at the end
2. comment // or /* ... */

Data types and variables

1. isNaN(NaN); // true
2. 2 / 0; // Infinity
3. 0 / 0; // NaN
4. 1 / 3 === (1 - 2 / 3); // false
5. 0 is a number, '' means empty string, null is empty value

String

1. multiple lines string could use `...`
2. var message = `Hi, ${name}, you are ${age} year old this year.`
3. toUpperCase, toLowerCase, indexOf, substring will NOT change the original string

Array

1. indexOf, slice, push, pop, unshift, shift, sort, reverse, splice, contac, join will NOT change the original string

Object

1. use '' if property name contain special character.

var A = {
  name: 'mock name',
  birthday: '01\/01\/2019',
  height: 6,
  'high-school': 'P A High'
}

Note: Cannot use A.high-school, use A['high-school'] // 'P A High'

2. hasOwnProperty() to decide whether the this prop is owned by the object itself.

Condition

Loop

Map & Set

1. Set only has keys, keys could not be same

iterable

1. for ... of

var s = new Set(['A', 'B', 'C']);
for (var x of s) {
    console.log(x);
}

2. forEach

var s = new Set(['A', 'B', 'C']);
s.forEach(function (element, sameElement, set) {
    console.log(element);
});

var m = new Map([[1, 'x'], [2, 'y'], [3, 'z']]);
m.forEach(function (value, key, map) {
    console.log(value);
});

var a = ['A', 'B', 'C'];
a.forEach(function (element) {
    console.log(element);
});