JavaScript Keywords
Keywords are reserved words that are part of the syntax in the programming language. For example,
const a = 'hello';
Here, const is a keyword that denotes that a is a constant.
Keywords cannot be used to name identifiers.
Here is the list of keywords available in JavaScript.
await |
break |
case |
catch |
class |
const |
continue |
debugger |
default |
delete |
do |
else |
enum |
export |
extends |
false |
finally |
for |
function |
if |
implements |
import |
in |
instanceof |
interface |
let |
new |
null |
package |
private |
protected |
public |
return |
super |
switch |
static |
this |
throw |
try |
true |
typeof |
var |
void |
while |
with |
yield |
JavaScript Identifiers
An identifier is a name that is given to entities like variables, functions, class, etc.
Rules for Naming JavaScript Identifiers
The rules for writing identifiers are:
- Identifier names must start with either a letter, an underscore
_, or the dollar sign$.For example,//valid const a = 'hello'; const _a = 'hello'; const $a = 'hello'; - Identifier names cannot start with numbers. For example,
//invalid const 1a = 'hello'; // this gives an error - JavaScript is case-sensitive. So y and Y are different identifiers. For example,
const y = "hi"; const Y = 5; console.log(y); // hi console.log(Y); // 5 - Keywords cannot be used as identifier names. For example,
//invalid const new = 5; // Error! new is a keyword.
Note: Though you can name identifiers in any way you want, it's a good practice to give a descriptive identifier name.
If you are using an identifier for a variable to store the number of students, it is better to use students or numberOfStudents rather than x or n.