JS

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JS

• Javascript

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Javascript

• Client Side Scripting Language
• Object Oriented
• Event Driven

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Places JS Lives

• An External File
• ltheadgt of an HTML file
• In the ltbodygt of an HTML page
• (after all the elements it may reference)
• JS can be used in multiple locations in the same
  HTML document

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A link to an external javascript document
A JS Script coded in the ltheadgt of an HTML
document
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External JS Files
Dont put another set of ltscriptgt tags inside
your external JS docs
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JS Inside HTML
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Variables

• All are untyped
• Local Variables
• Accessible only inside the current function
• Global by assignment

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Literals
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Operators
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Control Structure

• If
• If / else
• Switch
• For
• While
• For (object)

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IF

• If
• If / Else

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Switch
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Loops

• For
• While

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Looping over an Object
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Functions

• Declaring a Function
• Calling a Function

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Events
http//www.w3schools.com/jsref/jsref_events.asp
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Events
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JS Objects

• Properties
• A value held by an object
• Methods
• Act upon an object

A string property
A string method
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String Methods

• str.substr(start, length)
• Returns a sub string
• str.indexOf(seach)
• Returns positoin of the first instance of search
• str.replace(bad, good)
• Replaces bad text with good text
• str.split(delimiter)
• Breaks string into an array at every instance of
  delimiter

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String Properties

• str.len
• Returns length of a string

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Math Methods

• Math.ceil(x)
• Rounds up to the next integer value
• Max(x,y)
• Picks the larger of the two arguments
• Math.random()
• Returns a random number between 0.0 and 1.0

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Document Object

• Properties
• Document.URL
• Returns current url and query string
• Methods
• document.writeln()
• Prints a line in the current document
• Document.getElementById(id)
• returns an HTML element with the ID you provide