Syntax Error of function variable in Javascript

I am using node version 12.22.6.

I don’t understand, how this code is wrong.
I’m probably missing some important basic thing, but just cannot figure it out.

const change_vars = (var) => {
    console.log(var + " is a " + typeof(var) + "n");
}

const variables = [
    42,
    "42",
    {number: 42},
    {},
    true,
    undefined
]

variables.forEach(var => change_vars(var));

node vars.js

$ SyntaxError: Unexpected token ‘var’

Answer

You can’t use a reserved word to name your variables, you can find the full list here:

But some examples include:

break
case
catch
class
const
continue
debugger
default
delete
do
else
export
extends
finally
for
function
if
import
in
instanceof
new
return
super
switch
this
throw
try
typeof
var
void
while
with
yield

Long story short makes sure your variables are not named the same as the reserved words.