CIS 111 Lecture Notes - Lecture 3: Cascading Style Sheets, Web Application
5 Jun 2018
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Department
Course
Professor
Chpts 4,9,18,21,22,23 (Wk 3)
• What we will cover in class
o Function Expressions
o Program Structure
o Chpt 9: Where Should Your Code Live?
o Chpt 4: Conditional Statements & Logic Operators
o Chpt 5: Meet the Loops
o Chpts 21-23: Meet the DOM
• Function Declaration
o There are several ways to create a function in JavaScript
▪ First one is to use a function declaration.
//function declaration
function myFunction(param1, param2, …) {
//function code using param1, param2, …
}
//function call
myFunction(arg1, arg2, …);
• Notes
o Function definitions go at top
o Followed by IPO code
o Stored in a .js file
• Chpt 9: Separate .html & .js files
o Referencing the .js file
▪ Once you have your JavaScript file created, the second (and final) step is to
reference it in the HTML page. This is handled by your script tag. More
specifically, it is handled by your script tag’s src attribute that points to the
location of your JavaScript file:
<!DOCTYPE html>
<html>
<body>
<h1>Example</h1>
<script src=”example.js”></script>
</body>
</html>
• Chpt 4: Conditional Statements & Logic Ops
o Aka Selection Statements
▪ Problems that require an if statement to solve
• maxOf2
• isFactor
Chpts 4,9,18,21,22,23 (Wk 3)
• safeToProceed
• isWeekEnd
• isNaturalSeven
• isAlpha
• Is pf a factor of n?
var isFactor=function(n,pf)
if(n%pf==0) {
return true;
}
else
return false;
}
• If statement => Fork in the Road
var Safe_To_Proceed=true; //global symbolic constant
if(Safe_To_Proceed==true) {
alert(“You shall pass!”);
} else {
alert(‘“You shall not pass!”, quoth Gandalf.’);
}
• Conditional Operators
o Expression: anything that gives you a value
o Condition: an expression that evaluates to true or false
▪ Conditions are constructed using comparison operators and logic operators
Operator
When True
==
first expression evaluates to something equal to 2nd one
>=
first expression evaluates to something greater than or equal to 2nd
one
>
first expression evaluates to something greater than 2nd one
<=
first expression evaluates to something lesser than or equal to 2nd one
Document Summary
More specifically, it is handled by your script tag"s src attribute that points to the location of your javascript file: example fork in the road var safe_to_proceed=true; //global symbolic constant if(safe_to_proceed==true) { alert( you shall pass! ); } else { alert( you shall not pass! , quoth gandalf. "): conditional operators, expression: anything that gives you a value, condition: an expression that evaluates to true or false, conditions are constructed using comparison operators and logic operators. In javascript, days of the week are (0-6), where 0 is sin, 1 is mon, . //recognizer for weekends var isweekend=function(d){ var today = 5; alert(isweekend(today)); //returns false: natural seven .
