JavaScript Literals and Keywords
JavaScript Literals are the fixed value that cannot be changed, you do not need to specify any type of keyword to write literals. Literals are often used to initialize variables in programming, names of variables are string literals.
A JavaScript Literal can be a numeric, string, floating-point value, a boolean value or even an object. In simple words, any value is literal, if you write a string "Studytonight" is a literal, any number like 7007 is a literal, etc.
JavaScript supports various types of literals which are listed below:
JavaScript Numeric Literal
-
It can be expressed in the decimal(base 10), hexadecimal(base 16) or octal(base 8) format.
-
Decimal numeric literals consist of a sequence of digits (0-9) without a leading 0(zero).
-
Hexadecimal numeric literals include digits(0-9), letters (a-f) or (A-F).
-
Octal numeric literals include digits (0-7). A leading 0(zero) in a numeric literal indicates octal format.
JavaScript Numeric Literals Example
120 // decimal literal
021434 // octal literal
0x4567 // hexadecimal literal
JavaScript Floating-Point Literal
-
It contains a decimal point(.)
-
A fraction is a floating-point literal
-
It may contain an Exponent.
JavaScript Floating-Point Literal Example
6.99689 // floating-point literal
-167.39894 // negative floating-point literal
JavaScript Boolean Literal
Boolean literal supports two values only either true or false.
JavaScript Boolean Literal Example
true // Boolean literal
false // Boolean literal
JavaScript String Literal
A string literal is a combination of zero or more characters enclosed within a single('
) or double quotation marks ("
).
JavaScript String Literal Example
"Study" // String literal
'tonight' // String literal
String literals can have some special characters too which are tabled below.
String Special Characters:
Character |
Description |
\b
|
It represents a backspace. |
\f |
It represents a Form Feed. |
\n |
It represents a new line. |
\r |
It represents a carriage return. |
\t |
It represents a tab. |
\v |
It represents a vertical tab. |
\' |
It represents an apostrophe or single quote. |
\" |
It represents a double quote. |
\\ |
It represents a backslash character. |
\uXXXX |
It represents a Unicode character specified by a four-digit hexadecimal number. |
JavaScript Array Literal
-
An array literal is a list of zero or more expressions representing array elements that are enclosed in a square bracket([]
).
-
Whenever you create an array using an array literal, it is initialized with the elements specified in the square bracket.
JavaScript Array Literal Example
var emp = ["aman","anu","charita"]; // Array literal
JavaScript Regular Expression Literal
Regular Expression is a pattern, used to match a character or string in some text. It is created by enclosing the regular expression string between forward slashes.
JavaScript Regular Expression Example
var myregexp = /ab+c/; // Regular Expression literal
var myregexp = new RegExp("abc"); // Regular Expression literal
JavaScript Object Literal
It is a collection of key-value pairs enclosed in curly braces({}
). The key-value pair is separated by a comma.
JavaScript Object Literal Example
var games = {cricket :11, chess :2, carom: 4} // Object literal
JavaScript Keywords
Every programming language has its own keywords and reserved words. Every keyword is created to perform a specific task and the compiler or interpreter already knows about the built-in keywords and reserved words. JavaScript supports a rich set of keywords that are listed in the below table.
Keyword |
Description |
for |
The for keyword is used to create a for-loop. |
do/while |
The do and while both keywords are used to create loops in JavaScript. |
if/else |
The if and else keywords are used to create conditional statements. |
continue |
The continue keyword is used to resume the loop. |
break |
It is used to break the loop. |
function |
The function keyword is used to declare a function. |
debugger |
It is used to call the debugger function |
class |
The class keyword is used to declare the class. |
return |
Return keyword is used to return function from the function. |
float |
It is used to declare float type variable. |
int |
It is used to declare int type variable. |
private |
It is an access modifier. |
public |
Public is an access modifier that gives the class public access. |
var |
Var is used to declare a variable. |
switch |
The switch creates various statement blocks and executes only on block depending on the condition or the case. |
try/catch |
It creates a block for error handling of the statements. |
NOTE: While defining name of any function or variable, you should not use any keyword or reserved words.
In this tutorial, we learned about JavaScript literals, different types of literals along with examples. We also covered the JavaScript keywords and reserved words.