2. CHAPTER 2 BASIC JAVASCRIPT INSTRUCTIONS

3. STATEMENTS

4. Each individual step in a script is known as a statement.

5. Each statement should end with a semi-colon.

6. document.write(‘Welcome!’);
SEMI-COLON

7. COMMENTS

8. You should use comments to explain what your code does
You should use comments to explain what your code does. They help you remember it and others understand it.

9. MULTI-LINE COMMENTS

10. /* Anything between these characters is a comment and will not be processed. */

11. /* Anything between these characters is a comment and will not be processed. */

12. SINGLE-LINE COMMENTS

13. // Anything after the two // forward slashes is also // a comment and will not // be processed.

14. // Anything after the two // forward slashes is also // a comment and will not // be processed.

15. VARIABLES

16. Scripts often need to store bits of information temporarily in order to achieve their tasks.

17. These bits of information - or data - are stored in variables.

18. DECLARING A VARIABLE

19. var quantity;

20. var quantity;
KEYWORD

21. var quantity;
VARIABLE NAME

22. ASSIGNING A VALUE TO A VARIABLE

23. quantity = 3;

24. quantity = 3;
VARIABLE NAME

25. quantity = 3;
ASSIGNMENT OPERATOR

26. quantity = 3;
VALUE

27. DATA TYPES

28. JavaScript distinguishes between numbers, strings, and true or false values known as Booleans.

29. 1

30. 1
NUMBERS
0.75
NO QUOTES

31. 2 1
NUMBERS
0.75
NO QUOTES

32. 1 2 0.75 ‘Hi Ivy!’ NUMBERS STRINGS
NO QUOTES
STRINGS
‘Hi Ivy!’
ENCLOSED IN QUOTES WHICH CAN BE SINGLE OR DOUBLE QUOTES, BUT MUST MATCH

33. 3 1 2 0.75 ‘Hi Ivy!’ NUMBERS STRINGS
NO QUOTES
STRINGS
‘Hi Ivy!’
ENCLOSED IN QUOTES WHICH CAN BE SINGLE OR DOUBLE QUOTES, BUT MUST MATCH

34. 1 2 3 0.75 ‘Hi Ivy!’ true NUMBERS STRINGS BOOLEAN NO QUOTES
ENCLOSED IN QUOTES WHICH CAN BE SINGLE OR DOUBLE QUOTES, BUT MUST MATCH
BOOLEAN
true
EITHER TRUE OR FALSE

35. ARRAYS

36. An array is a special type of variable
An array is a special type of variable. It doesn’t just store one value; it stores a list of values.

37. colors = [ ];

38. colors = [‘pink’ ];

39. colors = [‘pink’,’yellow’ ];

40. colors = [‘pink’,‘yellow’,‘green’];

41. colors = [‘pink’,‘yellow’,‘green’];

42. colors = [‘pink’,‘yellow’,‘green’];

43. colors = [‘pink’,‘yellow’,‘green’];

44. colors = [‘pink’,‘yellow’,‘green’];

45. ARITHMETIC OPERATORS

46. JavaScript uses mathematics to get some tasks done.

47. var width = 3;

48. var width = 3; var height = 2;

49. var width = 3; var height = 2; area = width * height;

50. var width = 3; var height = 2; area = width * height;

51. var width = 3; var height = 2; area = width * height;

52. var width = 3; var height = 2; area = width * height;

53. 6

54. CONCATENATING STRINGS

55. There is just one string operator: the + symbol
There is just one string operator: the + symbol. It is used to join strings on either side of it.

56. var greeting = ‘Howdy ‘;

57. var greeting = ‘Howdy ‘; var name = ‘Molly’;

58. var greeting = ‘Howdy ‘; var name = ‘Molly’; var message = greeting + name;

59. var greeting = ‘Howdy ‘; var name = ‘Molly’; var message = greeting + name;

60. var greeting = ‘Howdy ‘; var name = ‘Molly’; var message = greeting + name;

61. var greeting = ‘Howdy ‘; var name = ‘Molly’; var message = greeting + name;

62. Howdy Molly