Operators in JS
Operators in Java Script
An expression is a combination of operators operands that can be evaluated. It may also include function calls which return values.
Examples
x = 7.5 // a numeric literal
“Hello India!” // a string literal
false // a Boolean literal
{feet:10, inches:5} // an object literal
[2,5,6,3,5,7] // an array literal
v= m + n; // the variable v
tot // the variable tot
ARITHMETIC OPERATORS
These are used to perform arithmetic/mathematical operations like subtraction, division, multiplication etc. Arithmetic operators work on one or more numerical values (either literals or variables) and return a single numerical value. The basic arithmetic operators are:
| Operator | Operator |
| + (Addition) | - (Subtraction) |
| * (Multiplication) | / (Division) |
| % (Modulus) |
Examples
var s = 10 + 20; // result: s=30
var h = 50 * 4; // result: h = 200
var d = 100 / 4; // result: d = 25
var r = 72 % 14; // result: r=2
Increment and decrement operators
These operators are used for increasing or decreasing the value of a variable by 1. Calculations performed using these operators are very fast.
++ Increment (By One)
-- Decrement (By One)
Example
var a = 15;
a++; // result: a = 16
var b = 20;
b—; // result: b = 19
ASSIGNMENT OPERATORS
It assigns the value of its right operand to its left operand. This operator is represented by equal sign(=).
Example
x = 100; // This statement assigns the value 100 to x.
JavaScript also supports shorthand operator for standard operations.
The shorthand operator with example :
| Shorthand operator | Example | is equivalent to |
| += | a + = b | a = a + b |
| -= | a - = b | a = a - b |
| *= | a * = b | a = a * b |
| /= | a / = b | a = a / b |
| %= | a % = b | a = a % b |
RELATIONAL (COMPARISON) OPERATORS
Relational Operators are some symbols which return a Boolean value true or false after evaluating the condition. For example x > y; returns a value true is value of variable x is greater than variable y.
Basic JavaScript comparison operators are given in the table below :
| Operator | Description | Example |
| = = | is equal to | 4 = = 8 returns false |
| ! = | is not equal to | 4 ! = 8 returns true |
| > | is greater than | 8 > 4 returns true |
| < | is less than | 8 > 4 returns false |
| < = | is less than or equal to | 8 < = 4 returns false |
| > = | is greater than or equal to | 8 > = 4 returns true |
Relational operators are functional for strings as well. The comparison takes place in alphabetical order. This alphabetical order is based on ASCII number. For example :
| Statement | Output |
| “zero” < “one” | false |
| “Zero” < “one” | true |
| 10 < 5 | false, numeric comparison. |
| “10” < “5” | true, string comparison. |
| “10” < 5 | false, numeric comparison; |
| “Ten” < 5 | Error occurs, “Ten” can not be converted into a number |
LOGICAL OPERATORS
Logical operators are used for combining two or more conditions. JavaScript has following three logical operators :
| Operator | Description with Example |
| && (AND) | returns true if both operands are true else it return false. |
| | | (OR) | returns false if both operands are false else it returns true. |
| ! (NOT) | returns true if the operand is false and false if operand is true. |
CONCATENATION OPERATOR
The + operator concatenates two string operands. The + operator gives priority to string operands over numeric operands It works from left to right. The results depend on the order in which operations are performed.
For example :
| Statement | Output |
| “Good” + “Morning” | “GoodMorning” |
| “5” + “10” | “510” |
| “Lucky” + 7 | “Lucky7” |
| 4 + 7 + “Delhi” | “11Delhi” |
| “Mumbai” + 0 +0+ 7 | “Mumbai007” |
Conditional Operator ( ? : )
The conditional operator is a special JavaScript operator that takes three operands. Hence, it is also called ternary operator. A conditional operator assigns a value to a variable based on the condition.
Syntax
var_name = (condition) ? v_1 : v_2If (condition) is true, the value v_1 is assigned to the variable, otherwise, it assigns the value v_2 to the variable.
For example
status = (age >= 18) ? “adult” : “minor”This statement assigns the value “adult” to the variable status if age is eighteen or more. Otherwise, it assigns the value “minor” to status.
New Operator:
new operator is used to create an instance and allocate memory to a user-defined or predefined object types.
Syntax
ObjectName = new objectType ( param1 [,param2] ...[,paramN])
Example
d = new Date(); // date assigns to object d
r = new rectangle(4, 5, 7, 8);
Delete Operator
The delete operator de-allocates (releases) the memory space that was allocated using the new operator by deleting an object, an object’s property or an element from an array.
The syntax is
delete object_name
delete object_name.property
delete array_name[index]
delete operator can be used to delete variables declared implicitly but not those declared with the var statement. The delete operator returns true if the operation is possible; it returns false if the operation is not possible.