JavaScript Relational operators are used to compare its operands and determine the relationship between them. They return a Boolean value (true or false) based on the comparison result.
Types of relation operators:
- in operator
- instanceof operator
We will explore all the above operators along with their basic implementation with the help of examples.
Method 1: in operator
The in-operator in JavaScript checks if a specified property exists in an object or if an element exists in an array. It returns a Boolean value.
Syntax:
prop in object
Example 1: Here is the basic example of using in operator.
Javascript
let languages = ["HTML", "CSS", "JavaScript"]; // true (index 1 exists in the array) console.log(1 in languages); // false (index 3 doesn't exist in the array) console.log(3 in languages); |
true false
Example 2: In this example, we are using in operator to check if the “name” property exists (true) and if the “address” property doesn’t exist (false).
Javascript
const Data = { name: "Rahul", age: 21, city: "Noida"}; // true ("name" property exists in the object) console.log("name" in Data); // false ("gender" property doesn't exist in the object) console.log("address" in Data); |
true false
Method 2: instanceof operator
The instanceof operator in JavaScript tests if an object is an instance of a particular class or constructor, returning a Boolean value.
Syntax:
let gfg = objectName instanceof objectType
Example 1: In this example, we are using instanceof operator.
Javascript
let languages = ["HTML", "CSS", "JavaScript"]; console.log(languages instanceof Array); console.log(languages instanceof Object); console.log(languages instanceof String); console.log(languages instanceof Number); |
true true false false
Example 2: In this example, the instanceof operator checks if myString is an instance of Object, Date, or String, and if myDate is an instance of Date, Object, or String.
Javascript
let myString = new String(); let myDate = new Date(); console.log(myString instanceof Object); console.log(myString instanceof Date); console.log(myString instanceof String); console.log(myDate instanceof Date); console.log(myDate instanceof Object); console.log(myDate instanceof String); |
true false true true true false
