Conditionals

Transcript

1. Conditionals forks in the road Tuesday, September 22, 2009
2. Tuesday, September 22, 2009
3. Tuesday, September 22, 2009
4. Tuesday, September 22, 2009
5. if statement execute some code only if a statement is true http://www.w3schools.com/JS/js_if_else.asp Tuesday, September 22, 2009
6. if Tuesday, September 22, 2009
7. if (conditional) Tuesday, September 22, 2009
8. if (conditional) { Tuesday, September 22, 2009
9. if (conditional) { // statement to be executed Tuesday, September 22, 2009
10. if (conditional) { // statement to be executed } Tuesday, September 22, 2009
11. true false Tuesday, September 22, 2009
12. var age = 60; var status = null; if (age > 62) { status = 'retired'; } status; // null Tuesday, September 22, 2009
13. var age = 60; var status = null; if (age > 62) { status = 'retired'; } status; // null 60 > 62 === false this never executes so status is never assigned and remains null Tuesday, September 22, 2009
14. var age = 65; var status = null; if (age > 62) { status = 'retired'; } status; // "retired" Tuesday, September 22, 2009
15. var age = 65; var status = null; if (age > 62) { status = 'retired'; } status; // "retired" 65 > 62 === true this executes so status is set to “retired” Tuesday, September 22, 2009
16. if...else statement execute some code if statement is true and some other code if statement is false http://www.w3schools.com/JS/js_if_else.asp Tuesday, September 22, 2009
17. if (conditional) { // statement if true } Tuesday, September 22, 2009
18. if (conditional) { // statement if true } else Tuesday, September 22, 2009
19. if (conditional) { // statement if true } else { Tuesday, September 22, 2009
20. if (conditional) { // statement if true } else { // statement if false Tuesday, September 22, 2009
21. if (conditional) { // statement if true } else { // statement if false } Tuesday, September 22, 2009
22. true false Tuesday, September 22, 2009
23. var age = 60; var status = null; if (age > 62) { status = 'retired'; } else { status = 'not retired'; } status; // "not retired" Tuesday, September 22, 2009
24. var age = 65; var status = null; if (age > 62) { status = 'retired'; } else { status = 'not retired'; } status; // "retired" Tuesday, September 22, 2009
25. if...else if...else statement execute some code if statement is true and some other code if statement is false http://www.w3schools.com/JS/js_if_else.asp Tuesday, September 22, 2009
26. if (conditional) { // statement if true } else if (conditional) { // statement if false and else if true } else { // statement if all false } Tuesday, September 22, 2009
27. if (conditional) { // statement if true } else if (conditional) { // whichever matches first } else if (conditional) { // whichever matches first } else if (conditional) { // whichever matches first } else { // statement if all false } Tuesday, September 22, 2009
28. var age = 19; var status = null; if (age >= 62) { status = 'retired'; } else if (age > 22 && age < 62) { status = 'working'; } else if (age >= 18 && age <= 22) { status = 'college'; } else { status = 'no responsibilities'; } status; Tuesday, September 22, 2009
29. switch statement select one of many blocks of code to execute http://www.w3schools.com/JS/js_switch.asp Tuesday, September 22, 2009
30. switch Tuesday, September 22, 2009
31. switch (value) Tuesday, September 22, 2009
32. switch (value) { Tuesday, September 22, 2009
33. switch (value) { case 1: Tuesday, September 22, 2009
34. switch (value) { case 1: // some code to execute Tuesday, September 22, 2009
35. switch (value) { case 1: // some code to execute break; Tuesday, September 22, 2009
36. switch (value) { case 1: // some code to execute break; case 2: // some code to execute break; Tuesday, September 22, 2009
37. switch (value) { case 1: // some code to execute break; case 2: // some code to execute break; default: // nothing matched so do this Tuesday, September 22, 2009
38. switch (value) { case 1: // some code to execute break; case 2: // some code to execute break; default: // nothing matched so do this similar to else in if...else Tuesday, September 22, 2009
39. switch (value) { case 1: // some code to execute break; case 2: // some code to execute break; default: // nothing matched so do this } Tuesday, September 22, 2009
40. var age = 18; switch (typeof(age)) { case 'number': "I'm a number!"; break; case 'string': "I'm a string!"; break; case 'boolean': "I'm a boolean!"; break; default: "I don't know what I am!"; } // "I'm a number!" Tuesday, September 22, 2009
41. for(action in json) { var selectors = json[action]; switch(action) { case 'replace' : for(selector in selectors) $(selector).html(selectors[selector]); break; case 'append' : for(selector in selectors) $(selector).append(selectors[selector]); break; case 'prepend' : for(selector in selectors) $(selector).prepend(selectors[selector]); break; case 'replaceWith' : for(selector in selectors) $(selector).replaceWith(selectors[selector]); break; case 'insertBefore' : for(selector in selectors) $(selectors[selector]).insertBefore($(selector)); break; case 'sidebar' : Sidebar.add(selectors); break; case 'remove' : $(selectors.join(',')).remove(); break; } } Tuesday, September 22, 2009
42. Review Tuesday, September 22, 2009
43. var age = 18; var teens = false; if (age > 12 && age < 20) { teens = true; } teens; Tuesday, September 22, 2009
44. var age = 18; var teens = false; if (age > 12 && age < 20) { teens = true; } teens; // true Tuesday, September 22, 2009
45. var days = ['sunday', 'monday', 'tuesday']; var first = days[0]; var week_starts_on_sunday = false; if (first === 'sunday') { week_starts_on_sunday = true; } week_starts_on_sunday; Tuesday, September 22, 2009
46. var days = ['sunday', 'monday', 'tuesday']; var first = days[0]; var week_starts_on_sunday = false; if (first === 'sunday') { week_starts_on_sunday = true; } week_starts_on_sunday; // true Tuesday, September 22, 2009
47. var days = ['monday', 'tuesday', 'sunday']; var first = days[0]; var week_starts_on_sunday = false; if (first === 'sunday') { week_starts_on_sunday = true; } week_starts_on_sunday; Tuesday, September 22, 2009
48. var days = ['monday', 'tuesday', 'sunday']; var first = days[0]; var week_starts_on_sunday = false; if (first === 'sunday') { week_starts_on_sunday = true; } week_starts_on_sunday; // false Tuesday, September 22, 2009
49. Assignment http://teaching.johnnunemaker.com/capp-30550/sessions/conditionals Tuesday, September 22, 2009