JavaScript Beginner Tutorial (Lesson 1)_Basic Knowledge

Interactivity! Most websites claim that interactivity means that you reach a new page when you click on a link, but strictly speaking, even when a web page has CGI language, it does not mean that it is truly interactive. Fill out the form, press submit, and wait...it's like throwing a bottle into the ocean and waiting for it to float back.

Fortunately, now we have Javascript, so web pages can actually interact as you want them to. Wherever the mouse moves, pictures are exchanged, and table elements interact with each other during the transfer process, and calculations can be performed without waiting for CGI reply results. There is no commit-waiting process - anything just happens when you use it.

The most outstanding thing about Javascript is that you can do a lot of things with a small program. You don't need a high-performance computer. The software only requires a word processing software and a browser. There is no need for a WEB server channel. You can do everything on your own computer.

Although it is very convenient to work, Javascript is a complete programming language, so when you finish learning more complex Javascript, you have learned some basics of computer programming.
If you want to continue learning other programming languages ​​such as Perl, C, C or Java, Javasript is an excellent introduction.
This week, we will start the first trilogy of five-day tutorials that will help you write some useful Javascript in no time. Unlike other specious Javascript tutorials, this tutorial will teach you how to build the JavaScript of your dreams. browser. As you walk through the examples in this tutorial, the browsers you build will become more and more exciting.
Here is a brief outline of what you will learn every day, and some examples of what you will learn.
Day 1: Introduction, some examples, and your first Javascript (example)
Day 2: Variables, if-then statements, link events, image exchange.
Day Three: Windows, Schemas, and File Object Modules
Day Four: Loops, Sequences, and Functions
Day Five: Tables, Tables, and More Tables.
Before we start, there are some important things to note first:
First of all, Javasript is not Java.
Second, Javascript is not Javascript! This refers to the way different browsers handle Javascript. Sometimes different versions of the same browser handle Javascript differently. This tutorial uses Netscape Navigator 3.0 as the standard. If there are any incompatibilities with other browsers, we will point them out. If you do not have Netscape 3.0, please download it now.
Third, this tutorial is not a substitute for a good reference book. Javascript resources are rich, good! Without further ado, let’s start writing some Javascript.

JavaScript usually appears between the tag and the tag.
Like HTML, JavaScript is text that can be viewed with word processing software and appears in HTML-related areas describing a page. (Although we have only seen JavaScript appearing in the header area of ​​an HTML page, it can also exist in the body. You will see this in the examples in the next lesson.
JavaScript starts with . The "alert" text is placed between quotes and ends with the tag.
Look! It's as simple as HTML. Yes... actually. There is a complication

In the previous example we ran into a problem where some older browsers didn't understand the <script> tag. These browsers will treat your JavaScript like HTML, so the page will look like this: <br/> //put up an alert box, to show how they work alert("Soon, I will overthrow my browser! "); <br/> Congratulations <br/> This is so bad! Fortunately, there is a solution in HTML comments: ="JavaScript">                                                                                                                                        ; <br/>                                                                                                            . If you don’t want to know, here is an introduction for you. <br/> There you go, believe it or not, you are about to prepare for your first JavaScript exercise. <br/> Are you exhausted? Before you hang up, take a minute to read our Lesson 1 review. <br/><br/></script>