JavaScript in operator is an inbuilt operator which is used to check whether a particular property exists in an object or not. It returns a boolean value true if the specified property is in an object, otherwise, it returns false.
Syntax:
prop in object
Parameters:
- prop: This parameter holds the string or symbol that represents a property name or array index.
- object: This parameter is an Object that is to be checked whether it contains the prop.
Return value:
This method returns a boolean value. The value true is returned if the specified property is found in an object, else it returns false.
Example 1: Below is an example of the in-operator.
function gfg() {
// Illustration of in operator
const array = [ 'geeks' , 'for' ,
'geeks' ]
// Output of the indexed number
console.log(0 in array);
// Output of the Value
console.log( 'for' in array);
// output of the Array property
console.log( 'length' in array);
} gfg(); |
true false true
Example 2: This example shows the use of the in operator in Javascript.
// Illustration of in operator const array = [ 'geeksforgeeks' , 'geeksfor' ,
'geeks' , 'geeks1' ]
// Output of the indexed number console.log(0 in array)
console.log(2 in array)
console.log(5 in array)
// Output of the Value console.log( 'for' in array)
console.log( 'geeksforgeeks' in array)
// output of the Array property console.log( 'length' in array)
|
true true false false false true
Example 3: This example shows the use of the in operator in Javascript.
// Illustration of in operator const object = { val1: 'Geeksforgeeks' ,
val2: 'Javascript' ,
val3: 'operator' ,
val4: 'in'
}; console.log( 'val1' in object);
delete object.val1;
console.log( 'val1' in object);
if ( 'val1' in object === false ) {
object.val1 = 'GEEKSFORGEEKS' ;
} console.log(object.val1); |
true false GEEKSFORGEEKS
Supported Browsers:
- Google Chrome
- Firefox
- Opera
- Safari
- Edge
- Internet Explorer
We have a complete list of Javascript Operators, to check those please go through the Javascript Operators Complete Reference article.