Reserved keywords

Tip: function, var, if ... Continue the list.
Try this:

var if = 100;

Answer: Look at the list:

break
case
class
catch
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        

Explanation: You need to know Reserved keywords because the could not be used as names for the variables