frontendmaster

I started to enroll kyle's lesson. When I did GFE problem, I sometimes been confused about why, I hope I could think more and learn deeper in this. Even I know I can't do it in one time.

Equality

==

• allow coercion
• toNumber()
  • compare as number
• can't coercion(object with other types)
• toPrimitive()

Corner case

• [] == ![] //true

===

• check type first
• if NaN, -0, they are not equal
• obj comparison
• need to point to the same object/array

Static type

Know your type will improve your code quality. not just depend on typescript.

scope

• target (assign value / declare) - runtime
• source (get value) - compile time

named function Pros

1. Reliable function self-reference (recursion, etc)
2. More debuggable stack traces
3. More self-documenting code
4. arrow function is anonymous function

advanced scope

• dynamic scope
• depends on where the function is called
• lexical scope
• depends on where the function is declared

block scope

• to solve name collision
• encapsulation
• use let, const (caused var will hoisting) to block scope
• use in condition or loop
• var can be reused in the same scope, but let, const can't
• store temporary value into block scope

const

• can't be reassigned
• can't be redeclared
• must be assigned when declare
• use with immutable primitive values(less confusion)

hoisting

• function execution first, then definition

Closure