1. Primitive
- number, boolean, string, null, undefined, symbol
- pass by value
- a copy of the value is created and passed/assigned instead of reference to the original value.
- any changes made to the value inside the function or to the new variable do not affect the original value
2. Non-Promitive
- object(function, array)
- pass by reference
- passing function arguments by reference to the memory address of an object or data structure instead of making a copy of the object.
- shallow copy: Object.assign({},obj) or Array.concat()- deep copy: JSON.parse(JSON.stringify())
3. Type Coercion
JS can be weird when it comes to type coercion. Try to guess what the output for each of the lines below are:
false == ""
false == []
false == {}
"" == 0
"" == []
"" == {}
0 == []
0 == {}
0 == null
true.toString() => 'true'
type of [] => 'object'
to check if it is array => Array.isArray()
4. static typing(vs dynamic)
1) props
- self documentation
- helpful in auto-completion
- likely to be less bugs
2) cons
- complexity
- learning curve
- slow speed in development
