introduce

How to embed script code in web pages

Comment

Variables - give things a name

Type of data - numbers, text, true vs false, etc.

Processing of text strings

Array array

if..else..

switch statement

while loop

for loop

function function

define a function

function expression

variable scope

Object

create an object

array in object

Update and delete attributes in objects

Add methods to objects

Loop through the properties in the output object

DOM operation document interface

Document tree

getElementById

getElementsByTagName

querySelector 与 querySelectorAll

Access an element's properties

Create and insert new nodes into the document

Insert node at specified position

deal with what happened

How to handle events

Handle the event that occurs using the object's event handler

Bind events to objects

dissemination of events

Change how events are propagated

Stop propagating event