JavaScript Overview
First, what JavaScript is the? What is the use
JS is a powerful scripting language on the web
Scripting language: Unable to perform independent, must be embedded into other languages, used in conjunction
Is parsed directly executed browser
Role: Control page effects show
JS may be dynamically controlled HTML elements
JS table item can be verified
JS CSS styles can be controlled
Second, the JavaScript language features and programming considerations
1, wherein
Javascript without compiling, direct your browser to be interpreted and executed
Javascript can not run alone, you must be embedded into the HTML code to run ·
Javascript execution process is performed successively from top to bottom
2 Notes
Javascript does not have permission (secure) access system files *
Because no need Javascript compiler, is from top to bottom in order to explain the implementation, so ensuring the readability of the case, allowing the use of chain programming
Javascript and java does not have any direct relationship
Three, JavaScript composition
ECMAScript：
It specifies the syntax and basic object of JS
JUDGMENT:
Document Object Model:Processing web contentMethods and interfaces
Mark the document type: HTML
GOOD:
Browser object model: andBrowser interactionMethods and interfaces
Four, JavaScript way of introduction
1, internal Screenplay
在当前页面内写<script></script>中
可以放置在任意位置
2, introduced from the outside (with more)
In HTML, by <script src="">introducing the label .jsfile
After the introduction of external, internal label not write code js
3, script tag placement standardization
Before the end of the label on the body
Pros: display HTML content holding priority load, last load script
