I'm trying to create a button that will increase and decrease the var speed variable

ex:

var speed = 5

<input onclick="??????" type="button" value="Increase Var Speed">
<input onclick="??????" type="button" value="Decrease Var Speed">

Help, anyone?

try this:
<input onclick="increase()" type="button" value="Increase Var Speed">
<input onclick="decrease()" type="button" value="Decrease Var Speed">

in your js code:

function increase()
{
speed = Number(speed ) + 1;
}

function decrease()
{
speed = Number(speed ) - 1;
}

it worked!

Thanks very much!!