1. JavaScript conditional

2. Boolean Logic Basis for modern computer logic
George Boole
Basis for modern computer logic
Works with only two values
George Boole was an english mathematician and philosopher. Born 1815, died 1864.

3. BOOLEAN VARIABLE OR EXPRESSION
Holds either true or false can pass as a literal Can be thought of as yes or no
Open excel – type true or false into a cell, and show that excel automatically capitlizes & centers it. TRUE & FALSE are special values in excel.

4. Is greater than or equal to
Boolean expressions
Creates a Boolean value from numbers or strings
Operator
Meaning ==
Is equal to !=
Is not equal
>
Is greater than
<
Is less than
>=
Is greater than or equal to
<=
Is less than or equal to

5. Conditionals Test if a Boolean expression is true or false
Allows a program to make a choice

6. IF … THEN … ELSE if (MUST BE LOWERCASE)
no else: do nothing if not true
else: one or the other
else if: series of choices

7. More complicated IF example
Let’s assign letter grades to students! – A – B – C – D <60 – F
Nested If: =IF(H2>=90, “A”, If(H2 >=80, “B”, “C or Below”))
Longer Nested if: =IF(H2>=90, "A", IF(H2>=80, "B", IF(H2>=70, "C", IF(H2 >=60, "D", "Fail"))))

8. Decision Tree grade < 60 F grade < 70 D grade < 80 CB A

9. In JavaScript
if (num < 60) { grade = "F"; } else if (num < 70) { grade = "D"; } else if (num < 80) { grade = "C"; } else if (num < 90) { grade = "B"; } else { grade = "A"; }

10. When you have more than one decision to make
nested else
When you have more than one decision to make

11. Example If you live in the United States: US?
Do you live in the District of Columbia or elsewhere?
If you don’t live in the United States:
Do you live in Europe or elsewhere?
US? no
yes
DC?
Europe?
yes no no
yes
DC state Europe other

12. In JavaScript
if (where == "US") { if (US == "DC") { report = "In DC"; } else { report = "In a state"; } } else if (continent == "Europe") { report = "In Europe"; } else report = "Other continent";

13. Combining Boolean expressions

14. Operations on Booleans
AND OR
Are all of them true?
&&
Is it a big dog?
(size==“big” && pet==“dog”)
Number between 5 and 10
(num>=5 && num<=10)
Are any of them true? ||
Is it either blue or black?
(color==“blue” || color==“black”)
Number less than 10 or greater than 20
(num<10 || num>20)