Core: Data Conversion with

1
Core Data Conversion with

• x 10 2 // 12
• x my word // my word
• x 10 2 // 12
• x 4 true // 5
• x 4 true // 4true
• x window 1 // object Window1
• x window true // object Windowtrue

2
Core More Data Conversion

• x Math.sin(1.234) // uses value 1.234
• if(nSum gt 22) ... // uses value 22
• x x - 1 // uses value 1
• x x - // uses value 0
• x x // converts x to a string
• x x y.toString() // x holds string value
• x (123).toString() // equivalent to x 123

3
Core Strings to numbers

• x parseInt(22 Acacia Avenue) // 22
• x parseFloat(5.87 pounds) // 5.87
• x parseInt(0xFF) // 255
• x parseInt(FF, 16) // 255
• x parseInt(two) // NaN or 0 (N2, IE3)
• x eval(3.2(1y)) // 3.2(1y)
• x eval(ygt3) // true or false

4
Client-Side Stuff

• ltscript languageSomeValidLanguagegt
• lt!-- code hiding from old browsers
• program stuff
• program stuff
• program stuff
• // end of code hiding --gt
• lt/scriptgt

5
Client-Side Stuff

• SomeValidLanguage is VBScript or JavaScript
  or JavaScript1.1 or JavaScript1.2...
• A ltscriptgt block may appear in the ltheadgt or
  ltbodygt block of a HTML file.
• Multiple, non-overlapping ltscriptgt blocks may
  appear.
• ltscriptgt blocks will be executed in the order
  they appear.

6
Event Handlers

• Some HTML tags support event handlers.
• This means that we can run simple code or invoke
  a JavaScript function when certain events occur.
• Examples
• ltbody onLoadbLoadedtrue nStartup22gt
• lta hrefnext.html onClickdoSomething(Next)
  gt

7
Events you may need

• Note Not all HTML objects support all events.
• Below are the main event handlers in no special
  order.
• onClick() onMouseOut() onMouseOver()
• onBlur() onFocus() onChange()
• onReset() onSubmit() onLoad()
• onUnload() onAbort() onError()

8
Timer Events

• JavaScript has a built in timer available
• setTimeout(myTickFunction(), 1000)
• The above sets the timer to wait for 1000
  milliseconds (one second), then call
  myTickFunction().
• The setTimeout() function only causes one timer
  tick event, it is not a clock.
• The clearTimeout() can cancel a pending event.