javascript notes-JS Tutorial-php.cn

day01
am:
Three basic knowledge of the front-end:
HTML: Specialized in writing web page content
CSS: Specialized in designing web page styles

JavaScript: Specialized in designing web page interaction language
Interaction: input data, program processes data, returns results

What is JavaScript:
1. A language specifically designed for web page interaction
2. Runs in a JavaScript interpreter
3 , "Explanation" execution - like reading a book
4. The largest language on the Internet: JSer

Brandon Edge: 4 languages pieced together - JavaScript

ECMAScript standard : JavaScript core syntax
Microsoft: JScript
ECMAScript standard: a piece of paper
Both JavaScript and JScript claim to fully implement the ECMAScript standard
W3C: DOM standard: a unified standard for specifically operating HTML elements, CSS styles, and events !

BOM: A tool dedicated to operating browser windows.
There is no standard, it is implemented by browser manufacturers themselves

JavaScript=ECMAScript DOM BOM

Mozilla Foundation——>Firefox
JSer’s biggest challenge: browser compatibility issues

Typical uses of JavaScript:
1. Client-side data calculation
2. Client-side form validation
3. Animation

JavaScript features: plain text; interpretation and execution; weak typing ; Based on object
How to use:
1. Use the js interpreter that comes with the browser:
F12——> Console
Write the script code at the cursor and press Enter to execute.
console: refers to the console: a window dedicated to debugging program output results.
log: A function provided by the console: output a line of log to the console.
Multiple lines: shift enter——>line break
** JavaScript is case sensitive! **
**Single and double quotes for strings are OK**
2. Install special interpreter software separately: node.js Chrome V8
win R——>cmd——>node
Exit: Ctrl c twice
Execute the .js file: 1. First cd to the path of the .js file
2. Enter on the node file name
3. Run with the webpage:
Browse The tool contains two tools:
Typesetting engine: specifically loads HTML content and CSS styles
Interpretation engine: specifically runs js scripts