An expression is a special kind of statement that evaluates to a value. Every expression is composed of −
Operands − Represents the data.
Operator − Defines how the operands will be processed to produce a value.
Consider the following expression- 2 + 3. Here in the expression, 2 and 3 are operands and the symbol + (plus) is the operator. JavaScript supports the following types of operators −
Assume the values in variables a and b are 10 and 5 respectively.
Operator | Function | Example |
---|---|---|
+ | Addition
Returns the sum of the operands. |
a + b is 15 |
- | Subtraction
Returns the difference of the values. |
a-b is 5 |
* | Multiplication
Returns the product of the values. |
a*b is 50 |
/ | Division
Performs a division operation and returns the quotient. |
a/b is 2 |
% | Modulus
Performs a division and returns the remainder. |
a%b is 0 |
++ | Increment
Increments the value of the variable by one. |
a++ is 11 |
-- | Decrement
Decrements the value of the variable by one. |
a-- is 9 |
Relational operators test or define the kind of relationship between two entities. Relational operators return a boolean value, i.e. true/false.
Assume the value of A is 10 and B is 20.
Operators | Description | Example |
---|---|---|
> | Greater than | (A > B) is False |
< | Lesser than | (A < B) is True |
>= | Greater than or equal to | (A >= B) is False |
<= | Lesser than or equal to | (A <= B) is True |
== | Equality | (A == B) is False |
!= | Not Equal | (A!= B) is True |
Logical operators are used to combine two or more conditions. Logical operators, too, return a Boolean value. Assume the value of variable A is 10 and B is 20.
Operators | Description | Example |
---|---|---|
&& |
And
The operator returns true only if all the expressions specified return true. |
(A > 10 && B > 10) is False |
|| |
Or
The operator returns true if at least one of the expressions specified return true. |
(A > 10 || B > 10) is True |
! |
Not
The operator returns the inverse of the expression’s result. For E.g.: !(7>5) returns false. |
!(A > 10) is True |
JavaScript supports the following bitwise operators. The following table summarizes JavaScript's bitwise operators.
Operators | Usage | Description |
---|---|---|
Bitwise AND | a & b | Returns a one in each bit position for which the corresponding bits of both operands are ones |
Bitwise OR | a | b | Returns a one in each bit position for which the corresponding bits of either or both operands are ones |
Bitwise XOR | a^{^}b | Returns a one in each bit position for which the corresponding bits of either but not both operands are ones |
Bitwise NOT | ~ a | Inverts the bits of its operand |
Left shift | a << b | Shifts a in binary representation b (< 32) bits to the left, shifting in zeroes from the right |
Sign-propagating right shift | a >> b | Shifts a in binary representation b (< 32) bits to the right, discarding bits shifted off |
Zero-fill right shift | a >>> b | Shifts a in binary representation b (< 32) bits to the right, discarding bits shifted off, and shifting in zeroes from the left |
The following table summarizes Assignment operators.
Sr.No | Operator & Description |
---|---|
1 |
= (Simple Assignment) Assigns values from the right side operand to the left side operand. Example − C = A + B will assign the value of A + B into C |
2 |
+= (Add and Assignment) It adds the right operand to the left operand and assigns the result to the left operand. Example − C += A is equivalent to C = C + A |
3 |
-= (Subtract and Assignment) It subtracts the right operand from the left operand and assigns the result to the left operand. Example C -= A is equivalent to C = C - A |
4 |
*= (Multiply and Assignment) It multiplies the right operand with the left operand and assigns the result to the left operand. Example C *= A is equivalent to C = C * A |
5 |
/= (Divide and Assignment) It divides the left operand with the right operand and assigns the result to the left operand. |
Note − The same logic applies to Bitwise operators, so they will become <<=, >>=, >>=, &=, |= and ^=.
Following are some of the miscellaneous operators.
Changes the sign of a value. The following program is an example of the same.
var x = 4 var y = -x; console.log("value of x: ",x); //outputs 4 console.log("value of y: ",y); //outputs -4
The following output is displayed on successful execution of the above program.
value of x: 4 value of y: -4
The + operator when applied to strings appends the second string to the first. The following program helps to understand this concept.
var msg = "hello"+"world" console.log(msg)
The following output is displayed on successful execution of the above program.
helloworld
The concatenation operation doesn’t add a space between the strings. Multiple strings can be concatenated in a single statement.
This operator is used to represent a conditional expression. The conditional operator is also sometimes referred to as the ternary operator. Following is the syntax.
Test ? expr1 : expr2
Where,
Test − Refers to the conditional expression
expr1 − Value returned if the condition is true
expr2 − Value returned if the condition is false
Example
var num = -2 var result = num > 0 ?"positive":"non-positive" console.log(result)
Line 2 checks whether the value in the variable num is greater than zero. If num is set to a value greater than zero, it returns the string “positive” else a “non-positive” string is returned.
The following output is displayed on successful execution of the above program.
non-positive
It is a unary operator. This operator returns the data type of the operand. The following table lists the data types and the values returned by the typeof operator in JavaScript.
Type | String Returned by typeof |
---|---|
Number | "number" |
String | "string" |
Boolean | "boolean" |
Object | "object" |
The following example code displays the number as the output.
var num = 12 console.log(typeof num); //output: number
The following output is displayed on successful execution of the above code.
number
ES6 provides a new operator called the spread operator. The spread operator is represented by three dots “...” . The spread operator converts an array into individual array elements.
The following example illustrates the use of spread operators in a function
<script> function addThreeNumbers(a,b,c){ return a+b+c; } const arr = [10,20,30] console.log('sum is :',addThreeNumbers(...arr)) console.log('sum is ',addThreeNumbers(...[1,2,3])) </script>
The output of the above code will be as seen below −
sum is : 60 sum is 6
The spread operator can be used to copy one array into another. It can also be used to concatenate two or more arrays. This is shown in the example below −
<script> //copy array using spread operator let source_arr = [10,20,30] let dest_arr = [...source_arr] console.log(dest_arr) //concatenate two arrays let arr1 = [10,20,30] let arr2 =[40,50,60] let arr3 = [...arr1,...arr2] console.log(arr3) </script>
The output of the above code will be as stated below −
[10, 20, 30] [10, 20, 30, 40, 50, 60]
The spread operator can be used to copy one object into another. It can also be used to concatenate two or more objects. This is shown in the example below −
<script> //copy object let student1 ={firstName:'Mohtashim',company:'TutorialsPoint'} let student2 ={...student1} console.log(student2) //concatenate objects let student3 = {lastName:'Mohammad'} let student4 = {...student1,...student3} console.log(student4) </script>
The output of the above code will be as given below −
{firstName: "Mohtashim", company: "TutorialsPoint"} {firstName: "Mohtashim", company: "TutorialsPoint", lastName: "Mohammad"}