1. Lecture # 13 JavaScript Functions: A Trip to the Grocery Store

2. Today Questions: Homework # 3? Lab # 4? Lab 5? 1.Introduce: How can you make an On-line Grocery List? 2.Explain: document.write, Text Concatenation, Debugging JavaScript Functions, loops for calculations 3.Demo: A Trip to the Grocery Store (10-15 min.) 4.Practice: You solve a problem: Add the Tax (10 min.) 5.Evaluate: Share and evaluate your solution 6.Re-practice:Write a JavaScript function using a Selection List to convert Celsius to Fahrenheit and vice versa Review for Quiz 2.

3. Today Questions: Homework # 3? Lab # 4? Lab 5? 1.Introduce: How can you make an On-line Grocery List? 2.Explain: document.write, Text Concatenation, Debugging JavaScript Functions, loops for calculations 3.Demo: A Trip to the Grocery Store (10-15 min.) 4.Practice: You solve a problem: Add the Tax (10 min.) 5.Evaluate: Share and evaluate your solution 6.Re-practice:Write a JavaScript function using a Selection List to convert Celsius to Fahrenheit and vice versa Review for Quiz 2.

4. Today Questions: Homework # 3? Lab # 4? Lab 5? 1.Introduce: How can you make an On-line Grocery List? 2.Explain: document.write, Text Concatenation, Debugging JavaScript Functions, loops for calculations 3.Demo: A Trip to the Grocery Store (10-15 min.) 4.Practice: You solve a problem: Add the Tax (10 min.) 5.Evaluate: Share and evaluate your solution 6.Re-practice:Write a JavaScript function using a Selection List to convert Celsius to Fahrenheit and vice versa Review for Quiz 2.

5. Today Questions: Homework # 3? Lab # 4? Lab 5? 1.Introduce: How can you make an On-line Grocery List? 2.Explain: document.write, Text Concatenation, Debugging JavaScript Functions, loops for calculations 3.Demo: A Trip to the Grocery Store (10-15 min.) 4.Practice: You solve a problem: Add the Tax (10 min.) 5.Evaluate: Share and evaluate your solution 6.Re-practice:Write a JavaScript function using a Selection List to convert Celsius to Fahrenheit and vice versa Review for Quiz 2.

6. Today Questions: Homework # 3? Lab # 4? Lab 5? 1.Introduce: How can you make an On-line Grocery List? 2.Explain: document.write, Text Concatenation, Debugging JavaScript Functions, loops for calculations 3.Demo: A Trip to the Grocery Store (10-15 min.) 4.Practice: You solve a problem: Add the Tax (10 min.) 5.Evaluate: Share and evaluate your solution 6.Re-practice:Write a JavaScript function using a Selection List to convert Celsius to Fahrenheit and vice versa Review for Quiz 2.

7. Today Questions: Homework # 3? Lab # 4? Lab 5? 1.Introduce: How can you make an On-line Grocery List? 2.Explain: document.write, Text Concatenation, Debugging JavaScript Functions, loops for calculations 3.Demo: A Trip to the Grocery Store (10-15 min.) 4.Practice: You solve a problem: Add the Tax (10 min.) 5.Evaluate: Share and evaluate your solution 6.Re-practice:Write a JavaScript function using a Selection List to convert Celsius to Fahrenheit and vice versa Review for Quiz 2.

8. But first …

9. Calculating Payments for a Loan

10. … if you don’t have a spreadsheet

11. The Payment “Power” Algorithm

12. How to code in javascript:

13. Why this?

14. How to code in javascript: Why this?

15. How to code it in javascript: And this?

16. A Trip to the Grocery Store

17. Lets first make a table of groceries

18. Now add a button

19. What else do we need?

20. What Functions Do We Need? function CalcSubTotal() –For each item, add price * quantity to subtotal –Fill in the subtotal text box –Return the subtotal function CalcSalesTax(subtotal) –Multiply 6.25% * subtotal –Fill in the tax text box –Return the tax

21. What Functions Do We Need? function CalcTotal() –Call CalcSubTotal –Call CalcTax –Add subtotal and sales tax together, and fill in the total text box

22. function CalcSubTotal() { subtotal = (demoform.milk.value * 2.59) + (demoform.bread.value * 1.09) + (demoform.oranges.value * 0.89) + (demoform.apples.value * 1.09) + (demoform.tortillas.value * 0.99) + (demoform.cheese.value * 2.49); subtotal = Math.round(subtotal*Math.pow(10,2))/Math.pow(10,2) ; demoform.subtotal.value = subtotal; return subtotal; }

23. Creating the Event Handler

24. Today Questions: Homework # 3? Lab # 4? Lab 5? 1.Introduce: How can you make an On-line Grocery List? 2.Explain: document.write, Text Concatenation, Debugging JavaScript Functions, loops for calculations 3.Demo: A Trip to the Grocery Store (10-15 min.) 4.Practice: You solve a problem: Add the Tax (10 min.) 5.Evaluate: Share and evaluate your solution 6.Re-practice:Write a JavaScript function using a Selection List to convert Celsius to Fahrenheit and vice versa Review for Quiz 2.

25. Group Exercise: Add the Tax

26. function CalcSalesTax(subtotal) { salestax = subtotal * 0.0625; demoform.tax.value = Math.round(salestax*Math.pow(10,2))/Math.pow(10,2); return salestax; }

27. function CalcTotal() { subtotal = CalcSubTotal(); salestax = CalcSalesTax(subtotal); total = subtotal + salestax; demoform.total.value = Math.round(total*Math.pow(10,2))/Math.pow(10,2); }

28. Today Questions: Homework # 3? Lab # 4? Lab 5? 1.Introduce: How can you make an On-line Grocery List? 2.Explain: document.write, Text Concatenation, Debugging JavaScript Functions, loops for calculations 3.Demo: A Trip to the Grocery Store (10-15 min.) 4.Practice: You solve a problem: Add the Tax (10 min.) 5.Evaluate: Share and evaluate your solution 6.Re-practice:Write a JavaScript function using a Selection List to convert Celsius to Fahrenheit and vice versa Review for Quiz 2.