What are the reserved keywords of javascript?

Hi friends we know what is  javascript.And next important thing is what are the reserved keywords of javascript.The reserved keywords are specified by ECMA .


javascript-reserved-keywords

Who was ECMA?

Actually ECMA is a scripting language  which works on the client web side .Javascript was developed by Brendan Eich of Netscape under the name of Mocha.Then name mocha was renamed to  LiveScript. Finally livescript was  renamed to JavaScript. Actually ECMA is the core of the javascript but not only contains all things of ECMA but also it has some other things which was not in ECMA. For standardization purpose javascript moved to ECMA specification with the name of ECMA-262.Now the javascript keywords are announced officially upto ECMA 5th script specifications.
Note: In this year(2015) ,ECMA 6th script will be announced officially.


Why it is essential to know about javascript reserved keywords?

Because we cannot use the reserved keywords as identifiers or variables or function names.The identifiers are nothing a combination of alphanumeric characters. Actually javascript reserved words  are identifiers but we should not  use it for function names and variables.Javascript reserved words are part of the language syntax. If we use a  reserved word as variables then it causes a compilation error when loading your script.

List of javascript reserved words

break
default
function
return
var
case
delete
if
switch
void
catch
do
in
this
while
const
else
instanceof
throw
with
continue
finally
let
try
debugger
for
new
typeof

List of future javascript reserve words


The following are future reserved words:
class
enum
export
extends
import
super

List of future javascript reserve words in strict mode

implements
interface
package
private
protected
public
static
yield

An Example to explain why we should not use javascript reserved words as variables


Open notepad copy and paste the below code and save as index.html.Then open with web browser you will get output 11 .I used x and y as variables here.


<p id="abc"></p>
<script>
var x = 5;
var y = 6;
document.getElementById("abc").innerHTML =
x+y;
</script>


Now again open notepad copy and paste the below code and save as index2.html.Then open with web browser you will not get output anything .I used continue and break as variables which are javascript reserved keywords.


<p id="abc"></p>
<script>
var continue = 5;
var break = 6;
document.getElementById("abc").innerHTML =
continue+break;
</script>
A sample animated gif tutorial was given below to explain why we should not use javascript reserved words.


dont-use-javascript-reserved-keywords-as-variables






Print Friendly and PDF
SHARE

About me

Hi. I am interested in blogging.And sometimes play with webdesign,web development,domain sale,designing logo and more.

    Blogger Comment
    Facebook Comment

0 comments :

Post a Comment