TypeScript - Operators


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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.

Show Examples

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.

Show Examples

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.

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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

Show Examples

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

Show Examples

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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