The following words cannot be used as variables, functions, methods, or object identifiers in coding JavaScript. These words have special meaning within the language and are predefined in the language’s formal specifications. Not all of them are currently in use. Some are reserved for future use.

Word Description
abstract
boolean
break Terminates the current loop, switch, or label statement and transfers program control to the statement following the terminated statement.
byte
case Evaluates an expression, matching the expression's value to a case label, and executes statements associated with that case.
catch Marks a block of statements to try, and specifies a response, should an exception be thrown.
char  
class  
const Declares a constant.
continue In a while loop, jumps back to the condition statement. In a for loop, jumps to the update statement.
default Evaluates an expression, matching the expression's value to a case label, if there is no matching case label  then executes statements associated with default.
do  
double  
else  
extends  
false  
final  
finally  
float  
for  
function  
goto  
if Executes a statement if a specified condition is true. If the condition is false, another statement can be executed.
implements  
import  
in  
instanceof  
int  
interface  
long  
native  
new  
null  
package  
private  
protected  
public  
return Specifies the value to be returned by a function.
short  
static  
super  
switch   Evaluates an expression, matching the expression's value to a case label, and executes statements associated with that case.
synchronized  
this  
throw  
throws  
transient  
true  
try  Marks a block of statements to try.
var  
void The void operator evaluates the given expression and then returns undefined
while  
with  

Reference/Credit

Reserved Words - MDN




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Author : Blue Cloud

Just a normal software developer who love to write code. Developing professional software since 1999. After working in the software industry for many years, I've started my own website to share knowledges and experiences.

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