An assignment simply stores a value in a variable and has the form:

<variable> = <expression>;

An expression can be a simple value but can also be more
complicated, so, rather than assigning a value to a variable, one
can also add a value to the current value of the variable using
**+=**, for example:

a = 100; // Assigning a simple
value

b = 200;

c = 300;

a += b; // Assigning with operation

a = b + c; // Assigning with expression

Similarly, you can subtract using **-=**, multiply using
***=**, divide using **/=**, or use bitwise operators using
**|=**, **&=**, or **^=**. You can also add or
subtract *one* from a value using **++**, **--**. For
further information see the section on Expressions.

Note that you *cannot* do the following (or any
variation):

var a, b, c;

a = b = c = 4;

And instead it should be done as:

a = 4;

b = 4;

c = 4;