CSC 230: The Week beginning Jan. 27

Provide a brief definition of the following terms (in the interface programming context):

• Reserved Word
• Comment
• Precedence
• Assignment statement
• Comparison Operator
• Boolean
• Condition

	var num1 = document.getElementById("txtNum").value;

	if (isNaN(num1) || num1=="") {
		alert("That's not a number");  //yell at user
		return;  //get out of here
	} 

1. Tip calculator update. Update your tip calculator program so that
   1. It displays the tip as well as the total (tip plus bill).
   2. The tip and total are displayed as currency -- with a dollar sign and two decimal places. See the ToFixed link above.
   3. Results are cleared if the changes are made to either the bill amount or the tip percent.
   4. Prior to any calculation the bill amount entered by the user is tested to see if it is actually a number and if it is positive. You must alert the user to the problem and code at least one other response (e.g. clear text, place focus in text input, change font to red, etc.)
   
   
   
2. Class standing. Write a page that prompts a user to enter the number of credits he or she has earned so far. The program should determine and display his or her class: freshman 1-23 credits, sophomore 24-53 credits, junior 54-83 credits or senior 84 credits and up.
   
   There are various ways to handle this problem. It can be handled using if and return. Another way to solve it is using the if -- else-if -- else structure http://www.w3schools.com/js/js_if_else.asp. Yet another way uses if along with the and (&&) logical operator. http://www.w3schools.com/js/js_comparisons.asp.
   
   
   
   
3. JavaScript Fever. Make a page that allows a user to enter a body temperature in degrees Fahrenheit and then determines a patient's status based on the following ranges.
   • T < 95; hypothermia
   • 95 <= T < 97.7; a little low
   • 97.7 <= T < 99.5; normal
   • 99.5 <= T < 104.0; fever
   • 104.0 <= T; hyperpyrexia