Arithmetic Operators
| Operator |
Description |
Example |
Result |
| + |
Addition
|
x=2
x+2
|
4
|
| - |
Subtraction
|
x=2
5-x
|
3
|
| * |
Multiplication
|
x=4
x*5 |
20
|
| / |
Division
|
15/5
5/2
|
3
2.5 |
| % |
Modulus (division remainder)
|
5%2
10%8
10%2 |
1
2
0 |
| ++ |
Increment |
x=5
x++
|
x=6
|
| -- |
Decrement |
x=5
x--
|
x=4
|
Assignment Operators
| Operator |
Example |
Is The Same As |
| = |
x=y |
"x equals y" |
| += |
x+=y
|
x=x+y; "x equals x plus y"
|
| -= |
x-=y
|
x=x-y; "x equals x minus y"
|
Comparison Operators
| Operator |
Description |
Example |
| == |
is equal to
|
5==8 returns false since 5 does not equal 8
|
| != |
is not equal
|
5!=8 returns true since 5 does not equal 8
|
| > |
is greater than
|
5>8 returns false since 5 is not greater than 8
|
| < |
is less than
|
5<8 returns true since 5 is less than 8
|
| >= |
is greater than or equal to
|
5>=8 returns false since 5 is not greater than or equal to 8 |
| <= |
is less than or equal to
|
5<=8 returns true since 5 is less than or equal to 8 |
Logical Operators
| Operator |
Description |
Example |
| && |
and
|
x=6
y=3
(x < 10 && y > 1) returns true
|
|
|| |
or
|
x=6
y=3(x==5 || y==5) returns false
|
|
! |
not
|
x=6
y=3
!(x==y) returns true
|
String Operator
A string is most often text, for example "Hello World!". To stick
two or more string variables together, use the + operator.
txt1="What a very"
txt2="spiffy day!"
txt3=txt1+txt2
|
The variable txt3 now contains "What a veryspiffy day!".
To add a space between two string variables, insert a space into the
expression, OR in one of the strings.
txt1="What a very"
txt2="spiffy day!"
txt3=txt1+" "+txt2
or
txt1="What a very "
txt2="spiffy day!"
txt3=txt1+txt2
|
The variable txt3 now contains "What a very spiffy day!".
Your Assignment
A'ight... Today you're going to be using alerts in two different Javascripts
with two highly annoying but amusing examples:
First, you're going to be doing a JavaScript alert box that counts to 100. Here's how:
|