JavaScript creates a simple script

1. Add JavaScript to the Web page

The first approach: write JavaScript code directly into an HTML document

<script></script>

The second approach: writing JavaScript code to a separate file

<script src= "File path" ></script>

For example:

<script src= ". /mycode.js "></script>

<script src= "Http://www.xxx.com/.../mycode.js" ></script>

2. JavaScript statements

JavaScript internal statements end with each statement ";"

To improve the readability of the code, in general, write only one statement per line

JavaScript comment statements are commonly used in two ways:

Single-line Comment

/* is commented

Lost content */

3. Variables

There are no strict rules for the naming of variables but we generally use only letters, numbers, dollar sign $ and underscores, and the style is usually camel (capitalized)

Definition: We use the keyword var to declare a variable

var Netprice;

Netprice = 8.99;

can be written

var netprice = 8.99;

If you want to assign a string to a variable, you need to quote the string in double or single quotes.

var stringname = "Xiangcunjiaoshihujin";

4. Operator

(1) Arithmetic operators

Plus +

Reduction

By

Remove

Residual%

Self-increment + +

Self-reduction--

(2) Operator precedence

Generally according to the operator priority level to

(3) + addition operation on both sides of the left is a string so the addition operation represents the connection operation

　　

var name = "Xiaohu"; var =+ age);

Will eventually get results displayed on the screen xiaohu22

5. Mouse events

Onclicks event handler (mouse click Trigger)

<input type= "button" onclick= "alert (' is ok! ')"  Value= "click Me"/>

When the mouse click on this button will pop up is ok!

OnMouseOver (mouse entry Trigger)

onmouseout (mouse off trigger)

JavaScript creates a simple script