Operators are what defines the operations to be performed on the variables in your script.
The = operator is the assignment operator and the value from whatever is on the right of this operator is assigned as the value to be contained in the variable to its left.
The + - * / and % operators work with numbers to add, subtract, multiply, divide, and take the remainder respectively.
The + operator also works with text strings to concatenate (join) them together. If either side of the + is a string then the operator will concatenate rather than add.
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
var hello, world, count;
count = 1;
count = count + 2;
hello = 'hello';
world = 'world';
hello + ' ' + world + count;