Introduction to JavaScript Advanced Programming

Preface:

It took me roughly a week to read half of this book carefully. These are the reading notes I made. I hope it can give people who read this book a rough reference. It may be a bit messy and not comprehensive at the moment, I will sort it out and add it later. (2017-7-17)

Chapter 1 JavaScriptIntroduction

Chapter 2 Used in HTMLJavaScript

## Chapter 3 Basic concepts

3.1.

Grammar

Case sensitive

Identifier(recommended to use camel casemyCar)

Comments // /**/

Strict mode(use strict)

Statement Recommendationvar diff-a-b; use semicolon, and if(test) { alert(test); }Also use {}

3.2 Keywords and reserved words

3.3 Variable

Uninitializedundefined var message = “hi”; message = 100; The type can be changed at will

Function test(){

Var a = “hi”; 局部

b = “hi”; 全局

}

Test(); alert(a); Error alert(b); hi

3.4 Data type

typeof

Undefined (defined but not assigned)

Null(null object pointer)

Boolean(Boolean valuetrue false The flow control statement will automatically execute the corresponding boolean Conversion)

Number

(octal0 decimal ten Hexadecimal 0x Floating point value rangeNaN Number conversionNumber parseInt )

String(String, no difference between single and double quotes, escape sequence, string characteristics, toString String)

Object(Object The basis of all objectsvar o = new Object();)

Function in ES is an object, not a data type.

3.5Operator

Unary operator ++ -- , + -(can be used to convert data types)

Bit operators Bitwise not~num1 Bitwise AND& Bitwise OR| Bitwise XOR^ Shift left<< Shift right>> Unsigned right Shift>>

Boolean operator ! && || Multiplicative operator* / % Additive operator+ - Relational operator< > <= >=

Equality operator == != === !== Conditional operator? ：

Assignment operator = *= /= %= += -= <<= >>= >> >=

Comma operator

3.6 Statement

3.7 Function

##arguments No overloading

Chapter 4 Variables, scope and memory issues

4.1

Values ​​of basic types and reference types

##Dynamic Attributes

(Reference types can dynamically add attributes)

Copy variable values

(The basic types are different Space, the reference type refers to the same space)

Pass parameters

(Same)

Detection type (typeof instanceof)

4.2Execution environment and scope

Scope Chain Extended scope chain(try-catch with) No block-level scope(if for Declare variable query identifier)

4.3Garbage collection

Strategy(Mark clear reference count ) Performance Issues Managing Memory

Chapter 5 Reference Type

5.1 ObjectType

Var person = {};(Suitable for passing a large number of parameters to functions) var parson = new Object();

Person["name"](Use # when using variables to represent attributes ##) person.name(Recommended)

5.2 Array

Type

Var colors = new Array(); var colors = Array(); var colors =[*****];

Colors[*] = *****; colors.length

Detect array: instanceof Array.isArray()

Conversion method: toString() valueOf() toLocaleString() join()

Stack method: push() pop()

Queue method: shift() unshift()

Reordering method: reverse() sort(You can add this parameter of comparison function)

Operation method:concat()The original has not changed and added slice()The original has not changed to intercept the segment splice()The original has changed Can be deleted or added

Position method: indexOf() lastIndexOf() Return the position of the item

Iteration method: every() filter() forEach() map() some() Each item is processed, but the original array will not change

Merge method: reduce()Order reduceRight()Reverse order The two items are always the same Traverse to the end

5.3 Date

Type

New Date()

Inside parse("May 25,2004") UTC(2005,0) Date.now()

Inherited method: toLocaleString( ) toString() valueOf()

Date formatting method: toDateString() toTimeString() toLocaleDateString() toLocaleTimeString() toUTCString()

Date/Time component method: too many specific readings

5.4RegExp

Type

Literal var pattern1 = / [bc]at / i;

Constructor var pattern2 = new RegExp(“ [bc]at ”, ” i ”);

RegExp

Instance attributeglobal ignoreCase lastIndex multiline source It’s useless

RegExpInstance method: exec() Capturing group(Capturing multiple groups of matches) text() Check if it matches once

RegExpConstructor attributes: There are a lot of them, used to see the relevant information of the latest match

Limitations of the pattern: Lack of advanced regular expression features supported by some languages ​​(Perl), but in most cases Enough

5.5 Function type Function is an object(is alsoFunction Instances of ), the function name is a pointer.

function sum(num1,num2) { }

Var sum = function(num1,num2){ };

No overloading: the function is an object and the function name is a pointer.

Function declaration and function expression: function ******* Function declaration promotion var sum = ** ***** Will not be promoted

Function internal attributes: argumentsObject (Attributecalleepoints to function) thisObject(Points to the environment object where the function executes ) Attribute caller (Points to the function that calls the current function, if it is a global scope function, the value is null)

Function attributes and methods:

Attributes(lengthDeclaration parameters Number prototypeInheritance)

Non-inherited method: call( ) apply() bind()

a.apply( b, c); a.call( b, d );

Run the function a in the environment object b, and pass in the parameters to ac( argumentor array) / d( Write each item out )

Var a = b.bind(c);

a is a function that runs in the c environment object

5.6Basic packaging type:

BooleanType: var booleanObject = new Boolean(true); It is recommended never to use Boolean objects.

NumberType: var numberObject = new Number(10); toFixed( ) toExponential() toPrecision()

It is also recommended not to instantiate the Number type directly.

String Type: var stringObject = new String(“hello world”); lengthAttributes

1.Character method: charAt()or string[] Return the corresponding character charCodeAt() Return the corresponding character encoding

2. String operation method:

concat() or# The ##+ operator looks the same as the array's concat()

Slice() substring() substr()

Intercept string, three are very flexible

3.

String position method: indexOf( ) lastIndexOf()

4.trim()

Method Remove all prefix and suffix spaces trimLeft() trimRight()

5. String case conversion method

toLowerCase() toUpperCase()

Classic method

toLocaleLowerCase() toLocaleUpperCase()

Specific regions This is more secure

6. String pattern matching method

match()

The same essence as RegExpexec() returns the string that matches Array

search()

Returns the index of the first matching item otherwise returns -1

replase()

Match and replace the string

split()

Match the delimiter to generate an array

7.localeCompare()

Compare two strings

8.fromCharCode()

Static method Encode multiple characters Become a string

9.HTML

method For example big() string

5.7

Single built-in object

1.Global

Object

URL

Encoding method:

encodeURI()

Entire encodeURIComponent() some A paragraph of encoding

decodeURI()

The whole decodeURIComponent() A certain paragraph of decoding

eval()

Method Very powerful and very dangerousECMAScriptParser

Global

Object properties undefined、Array......are all properties

Web

The browser implements the global object as a part of the window object

2.Math

Object

Math

Properties of the object Some special values ​​such as π

min() max()

Method

Rounding method: convert decimal value into integer

Math.ceil(25) Add one Math.floor(25) Back one Math.round(25) Rounding

random()Method [0,1) Random number between

Other methods Too much reading

Chapter Six Object-oriented programming

6.1Understanding objects

6.1.1Attribute type:

Data attribute: 4 attributes

Accessor properties: does not contain data values 4 properties are defined via Object.defineProperty()

6.1.2Define multiple properties: Object.defineProperties() Can be a data property or an accessor property.

6.1.3Read property characteristics: Object.getOwnPropertyDescriptor()

6.2Create Object

6.2.1Factory Mode(看书)

6.2.2Constructor pattern(看书 new constructor )

6.2.3Prototype pattern:

1. Understand the prototype object

2.Prototype and inoperator(in for-in)

3.Simpler prototype syntax(Object literal to access the object)

4.The dynamics of the prototype(The prototype can be replaced by another object, but it will be invalid for the instance that has been created)

5.Prototype of native object( is to use prototype mode, you can define new methods in it, but it is not recommended)

6. Problem with prototype objects: There are no properties belonging to the instance itself

6.2.4Use the constructor pattern and prototype pattern in combination

The most common mode, instances have their own properties and methods, and some are shared.

6.2.5Dynamic prototype mode

Add a judgment statement to the above mode to dynamically add a judgment statement to the prototype Add method.

6.2.6Parasite Constructor Pattern

The only difference between the Parasitic Constructor Pattern and the Factory Pattern is one new, and it has multiple return. The returned object has nothing to do with the constructor, so the instanceof operator cannot be used to determine the object type. Not recommended.

6.2.7Safe constructor pattern

is similar to the parasitic constructor pattern, but does not use this and new. instanceofcannot be detected either

6.3Inheritance

6.3.1Prototype chain Prototype search mechanism

1.Don’t forget the default prototype: the default for all functions Prototypes are all instances of Object.

2.Determine the relationship between prototype and instance: instanceof isPrototypeOf()

3. Carefully Define methods: New methods must be defined after the instance replaces the prototype.

4. Prototype chain problem:

Attributes outside the prototype are also inherited

When creating an instance of a subtype, parameters cannot be passed to the constructor of the supertype.

Rarely used alone.

6.3.2 Borrow the constructor using call or apply Inherit and pass parameters but only use the constructor pattern.

is also rarely used alone.

6.3.3Combined inheritance

Prototype chain implementation Prototype attributes and Inheritance of methods

Use constructor to implement Inheritance of instance attributes

The most commonly used inheritance method

6.3.4Prototypal inheritance(看书)

The constructor is not used The retained type can be used, but the properties of the reference type will be shared like the prototype mode.

6.3.5Parasitic inheritance(看书)

Constructor is not considered Can be used But function reuse cannot be achieved

6.3.6Parasitic combined inheritance(看书)

Problem with compositional inheritance: the supertype's constructor is called twice, resulting in duplicate properties in the instance and prototype.

Parasitic combined inheritance solves this problem and becomes the most ideal inheritance paradigm.

Chapter 7 Function expression

How to define a function:

Function declaration(Function declaration is promoted with name)

Function expression( name is empty anonymous function/Named general function expressions are anonymous functions)

7.1Recursion

Strict mode cannot be used arguments.callee Named function expressions can be used.

7.2Closure: A function that has access to a variable in the scope of another function

Self-summary: Closures are functions, generally anonymous functions are used

1. Closures can access variables in returned external functions.

2.The active object of another function will be saved until the closure's scope chain is destroyed.

7.2.1 Closures and variables

Side effects: closures are saved in the scope chain is the entire variable object, so the variable returned is the last value saved.

For example, in the for loop, unsatisfactory situations will occur.

7.2.2AboutthisObject

The this object in the closure, the closure may be placed on the global object in some special circumstances, so this changes. Know.

7.2.3Memory leak

Use closures to ensure normal memory recovery

7.3Imitate block-level scope

Use anonymous self-executing functions to imitate.

Self-summary effect:

1.It will be destroyed after internal execution.

2.Anonymous self-executing functions can reduce pollution of global methods and properties.

Closures have a memory problem, and it is very comfortable to use this combination.

7.4Private variables

Everything on the object is public Everything in the function is private

Create the public method of the function through closure(Privileged method) ---------Used to obtain private variables

Created in the constructor                                                                                                                                                                                                                                                                                                         ##this.****** = function(){ **** }; But each instantiation will rebuild a set of methods, which is wasteful.

7.4.1Static private variables                                                                           An instance does not have its own private properties

Static uses

Private scope

Global construction through closure Create privileged methods in the function's prototype.

Improves code reusability, but each instance does not have its own private variables. (Because this is called a static private variable)

Use instance variables or static private variables, depending on the specific needs.

7.4.2Module Mode                                                                                     Literal An instance object

Create private variables and privileged methods for a singleton

(

Singleton: an object with only one instance

) Define private variables and methods inside the anonymous function, and then use an object literal as the return value of the function.

7.4.3

Enhanced module mode

Must be an instance of a certain type , some properties or methods must also be added.

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