Basic syntax for JavaScript (i)

A common table unit is known as:

TextBox (Text),

Password box (password),

Multiline text box (<textarea>)

Radio button (radio),

check box (checkbox),

list box (<select> and <option>)

Buttons (button, submit, and reset)

Second, why to learn JavaScript

1. Form verification-Reduce server-side pressure

2. Page dynamic effects

3. Dynamically change page content

What are the components of JavaScript?

Made up of Ecmascript,dom (Document Object model), BOM (Browser object model)

IV. basic structure of JavaScript scripts

<script type= "Text/javascript" >

<!--JavaScript statements; -

</script >

V. Declaration and assignment of JavaScript variables

1. Declare the variable to be re-assigned (var width; width = 5)

2. Simultaneous declaration and assignment variable (var catname= "Leather";)

3. Do not declare direct assignment (width=5)

Vi. data type typeof The return value of the detection variable

Undefined Boolean string number null

The return value of the typeof operator is as follows:

undefined: The variable is declared but not assigned

string: A character literal that is declared in single or double quotation marks

Boolean: True or False

number: integer or floating-point number

object: Objects, arrays, and Null in JavaScript

Seven, operational symbols

1. Arithmetic operators (+,-,*,/,%,++,--)

2. Assignment operator (=,==)

3. Comparison operator (> < >= <= = = =)

4. Logical operators (&& | | !)

Viii. notes

1. Single-line comments start with // , end at end of line,

2. Multi-line comments start with/ * , End with * /, sign/ * ... * /indication

Nine, common input/output

Alert ()

Alert ("hint message");//Popup window hint

Input box hint

Prompt () prompt ("Prompt information", "Default information for Input box");

Prompt ("Please enter name", "Zhang San"); Prompt ("Please enter name");

Basic syntax for JavaScript (i)