heap Heap value type
Original type (primitive type)
undefined:undefined (Note case: type/value, same below)
Null:null (Undefined derived from null)
Boolen:true/false
Number:number.max_value/number.min_value/nan isNaN () function (note: Changes in the new version are available)
String:
Type conversions:
Boolen ()/number ()/string () * * refers to the type name
ToString (): ToString (2/8/16)
Intparse ()/floatparse ():
Stack Stack Reference type
Predefined
Object:
Boolen:
Number:tofixed ()
String: (abbreviated)
Instanceof ()
operator
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Label Label:
Object:
Object is a unordered (distinct from array) collection of name-value pairs (properties and methods)
Create: New and {}
Extensions: Add new attributes to an object (meaning to modify the instance at run time!) ) Operator: "." or "[]"
Constructor: You can judge a type, but unlike typeof, it returns an object
Prototype: Structure of objects
properties: (variable)
Scope
var: local variable, that is, the variable scope is the most inner function body
Method: (function)
JavaScript supports the first class (first-class) function, which is processing the function as an object. So it can be assigned to a variable (=), stored as an array element, as a return value, and so on.
This
Simple memory:
Global functions (simple-declared functions in a page): Window
DOM event handler (function that handles DOM events): The DOM element associated with the event (attention event bubbling)
Constructor: the instance itself
Understand:
Typically, this is always pointing to the object that calls the function (the so-called "run-time determination")
Special case: Apply () and call (), which point to the parameter object of the above two functions
Closures:
Forms of Expression:
functions defined within a function
Function:
Ability to read other function internal variables
To connect functions inside and outside functions
Keep the values of these variables always in memory
Array:
An ordered (distinct from object) set of values that can be of different types
Created: New Array () or []
