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What is an Operator?
An operator defines some function that will be performed on the data. The data on which operators work are called operands. Consider the following expression −
7 + 5 = 12
Here, the values 7, 5, and 12 are operands, while + and = are operators.
The major operators in TypeScript can be classified as −
- Arithmetic operators
- Logical operators
- Relational operators
- Bitwise operators
- Assignment operators
- Ternary/conditional operator
- String operator
- Type Operator
Arithmetic Operators
Assume the values in variables a and b are 10 and 5 respectively.
Operator | Description | 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 division operation and returns the quotient | a / b is 2 |
% (Modulus) | performs division operation 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
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.
Operator | 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
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.
Operator | 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.: !(>5) returns false | !(A >10 ) is True |
Bitwise Operators
Assume variable A = 2 and B = 3
Operator | Description | Example |
---|---|---|
& (Bitwise AND) | It performs a Boolean AND operation on each bit of its integer arguments. | (A & B) is 2 |
| (BitWise OR) | It performs a Boolean OR operation on each bit of its integer arguments. | (A | B) is 3 |
^ (Bitwise XOR) | It performs a Boolean exclusive OR operation on each bit of its integer arguments. Exclusive OR means that either operand one is true or operand two is true, but not both. | (A ^ B) is 1 |
~ (Bitwise Not) | It is a unary operator and operates by reversing all the bits in the operand. | (~B) is -4 |
<< (Left Shift) | It moves all the bits in its first operand to the left by the number of places specified in the second operand. New bits are filled with zeros. Shifting a value left by one position is equivalent to multiplying it by 2, shifting two positions is equivalent to multiplying by 4, and so on. | (A << 1) is 4 |
>> (Right Shift) | Binary Right Shift Operator. The left operand’s value is moved right by the number of bits specified by the right operand. | (A >> 1) is 1 |
>>> (Right shift with Zero) | This operator is just like the >> operator, except that the bits shifted in on the left are always zero. | (A >>> 1) is 1 |
Assignment Operators
Operator | Description | Example |
---|---|---|
= (Simple Assignment) | Assigns values from the right side operand to the left side operand | C = A + B will assign the value of A + B into C |
+= (Add and Assignment) | It adds the right operand to the left operand and assigns the result to the left operand. | C += A is equivalent to C = C + A |
-= (Subtract and Assignment) | It subtracts the right operand from the left operand and assigns the result to the left operand. | C -= A is equivalent to C = C – A |
*= (Multiply and Assignment) | It multiplies the right operand with the left operand and assigns the result to the left operand. | C *= A is equivalent to C = C * A |
/= (Divide and Assignment) | It divides the left operand with the right operand and assigns the result to the left operand. |
Note − Same logic applies to Bitwise operators, so they will become <<=, >>=, >>=, &=, |= and ^=.
Miscellaneous Operators
The negation operator (-)
Changes the sign of a value. Let’s take an example.
var x:number = 4 var y = -x; console.log("value of x: ",x); //outputs 4 console.log("value of y: ",y); //outputs -4
On compiling, it will generate following JavaScript code.
//Generated by typescript 1.8.10 var x = 4; var y = -x; console.log("value of x: ", x); //outputs 4 console.log("value of y: ", y); //outputs -4
It will produce the following output −
value of x: 4 value of y: -4
String Operators: Concatenation operator (+)
The + operator when applied to strings appends the second string to the first. The following example helps us to understand this concept.
var msg:string = "hello"+"world" console.log(msg)
On compiling, it will generate following JavaScript code.
//Generated by typescript 1.8.10 var msg = "hello" + "world"; console.log(msg);
It will produce the following output −
helloworld
The concatenation operation doesn’t add a space between strings. Multiple strings can be concatenated in a single statement.
Conditional Operator (?)
This operator is used to represent a conditional expression. The conditional operator is also sometimes referred to as the ternary operator. The syntax is as given below −
Test ? expr1 : expr2
-
Test − refers to the conditional expression
-
expr1 − value returned if the condition is true
-
expr2 − value returned if the condition is false
Let’s take a look at the following code −
var num:number = -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 the string “non-positive” is returned.
On compiling, it will generate following JavaScript code.
//Generated by typescript 1.8.10 var num = -2; var result = num > 0 ? "positive" : "non-positive"; console.log(result);
The above code snippet will produce the following output −
non-positive
Type Operators
typeof operator
It is a unary operator. This operator returns the data type of the operand. Take a look at the following example −
var num = 12 console.log(typeof num); //output: number
On compiling, it will generate following JavaScript code.
//Generated by typescript 1.8.10 var num = 12; console.log(typeof num); //output: number
It will produce the following output −
number
instanceof
This operator can be used to test if an object is of a specified type or not. The use of instanceof operator is discussed in the chapter classes.
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