![Model parameterization and experimental design issues in ...parameters [see, e.g., Dean and Dalrymple, 2001]. These parameters, while ostensibly functions of wave climate, sediment](https://static.fdocuments.in/doc/165x107/6126fb9e715526692c3e932a/model-parameterization-and-experimental-design-issues-in-parameters-see-eg.jpg)
Functions and Parameters
23
Functions and Parameters
description
Functions and Parameters. Structured Programming. Modular, Structured Programs. Program: Sequences, conditionals, and loops. Cohesive blocks of code. Request that blocks of code do work. Transition to objects. Task. Generate payroll for employees. Steps. Retrieve employee information. - PowerPoint PPT Presentation
Transcript of Functions and Parameters
Functions and Parameters
Structured Programming
Modular, Structured Programs
• Program:– Sequences, conditionals, and loops.– Cohesive blocks of code.– Request that blocks of code do work.
Transition to objects.
Task
• Generate payroll for employees.
Steps
• Retrieve employee information.• Retrieve payroll data for employee.• Calculate gross pay.• Calculate federal income tax.• Calculate FICA tax.• Calculate state tax.• Calculate net pay.• Transfer net pay to employee account.• Transfer taxes to tax liability accounts.• Generate pay statement.
StructureGet Employee Data Retrieve employee information
Retrieve payroll data for employee
Calculate gross pay
Calculate federal income taxCalculate FICA taxCalculate state tax
Calculate net pay
Transfer net pay to employee accountTransfer taxes to tax liability accounts
Compute Net Pay
Deposit Funds
Prepare Pay Statement
Employees Remaining? Generate pay statement
ModulesGet Employee Data Retrieve employee information
Retrieve payroll data for employee
Calculate gross pay
Calculate federal income taxCalculate FICA taxCalculate state tax
Calculate net pay
Transfer net pay to employee accountTransfer taxes to tax liability accounts
Generate pay statement
Compute Net Pay
Deposit Funds
Prepare Pay Statement
Employees Remaining?
Benefits
• Easier programming.
• Easier, better testing – modules.
• Easier maintenance.
• Reusable modules.
Basic Functions
Function
• Module of code.
• Each function should:– Perform a well-defined task.– Be self contained.– Receive the minimum data to perform task.
• Return value is optional.
<html><head><script type="text/javascript">
function popupMessage(){
alert('Hello\nHow are you today?')}
</script></head><body><script type="text/javascript">
popupMessage()alert('Hello’)
</script></body></html>
Function Declaration
function popupMessage(){
alert('Hello\nHow are you today?')}
declaration name parameter list
start of function code
end of function code
Parameters
Function with Parameter
function popupMessage(message){
alert(message)}
parameter
use of parameter in function
popupMessage('Oh no!')show = 'JavaScript is fun!'popupMessage('show')popupMessage(show)
function call using a parameter
Oh no!JavaScript is fun!
Multiple Parameters
function popupMessage(line1, line2){
alert(line1 + '\n' + line2)}
popupMessage('Oh no!', 'Mr. Bill')show1 = 'JavaScript is fun!'show2 = 'HTML is easy'popupMessage(show1, show2)
parameters
function call with multiple parameters
Image Rollovers
Implementation Overview
• Precaching.
• Multiple images.
• OnMouseOver event.
• OnMouseOut event.
<body><img id="pic1" src="netpic1.gif" />
<script type="text/javascript">
alert(document.images[0].src)
alert(document.images.pic1.src)
alert(document.getElementById('pic1').src)
</script></body>
index
id
by id using method
images collection
images collection
Referencing Elements
getElementById
document.getElementById(id).target
target’s id
property or method based on target’s type (e.g., img)
Recommended for accessing HTML elements in JavaScript
Debugging
Techniques
• Browser options:– IE: Enable script error notifications.– Mozilla: Use JavaScript console.
• Debug messages:– Display “current position” alerts in code.– Display intermediate computations.
<script type="text/javascript">
var screenHeight = 0var screenWidth = 0var usableHeight = 0var usableWidth = 0var verticalWaste = 0var horizontalWaste = 0
screenHeight = screen.availHeightscreenWidth = screen.availWidthusableHeight = document.body.clientHeightusableWidth = documnet.body.clientWidthverticalWaste = screenHeight - usableHeighthorizontalWaste = screenWidth – usableWidth
alert('Vertical Waste: ' + verticalWaste + '\n' + 'Horizontal Waste: ' + horizontalWaste)
</script>
alert(‘ok so far’)alert(‘ok so far’)alert(‘ok so far’)alert(‘ok so far’)
alert(screenHeight)
