(3) JavaScript learning notes-functions, objects, Arrays

I. Functions

Definition:

 
Function Square (x) {return x * x}
 

Ii. object,Set of named Data

1. Create

 
VaR o = new object (); var now = new date (); var pattern = new Regexp ("\ sjava \ s", "I ");
 

2. Call attributes

 
VaR poit = new object (); point. x = 2.3; point. Y =-1.2;
 

3. object initialization. The object direct quantity is composed of a list, which is an attribute/value pair separated by colons.

 
VaR point = {X: 2.3, Y:-1.2 };
 

4. Objects can also be nested

 
VaR rectangle = {upperleft: {X: 2, Y: 2}; lowerright: {X: 2, Y: 4 }}
 

5. the attribute value in the object does not need to be a constant, but can be any expression. The attribute name can be a string rather than an identifier.

3. Array

1. Arrays can store any JS data type.

 
Document. Images [1]. Width
 

2. Create an array using the constructor array ()

 
VaR A = new array (); A [0] = 1.2; A [1] = "bingzong"; A [2] = true; A [3] = {X: 1, Y: 3} // create an array var A = new array (1.2, "Mr. sao ", true); // only one parameter is passed. The specified parameter is the array length var A = new array (10 ); // You can also use the syntax var A = [1.2, "mr. Sao", true] // You can also store undefined elements var A = [1, 5]