JavaScript in operator
Below is the example of the in operator.
Example 1:
<script>
function
gfg() {
// Illustration of in operator
const array = [
'geeks'
,
'for'
,
'geeks'
]
// Output of the indexed number
document.write(0
in
array);
// Output of the Value
document.write(
'for'
in
array);
// output of the Array property
document.write(
'length'
in
array);
}
gfg();
</script>
Output:
true false true
The in operator is an inbuilt operator in JavaScript which is used to check whether a particular property exists in an object or not. It returns boolean value true if the specified property is in an object, otherwise it returns false.
Syntax:
prop in object
Parameters: This function accepts the following parameter as mentioned above and described below:
- prop: This parameter holds the string or symbol that represents a property name or array index.
- object: This parameter is an Object which to be checked whether it contains the prop.
Return value: This method returns an boolean values :
- true: The value true is returned if the specified property is found in an object.
- false: The value false is returned if the specified property is not found in an object.
Below examples illustrate the in operator in JavaScript:
Example 1:
<script> // 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) </script> |
Output:
> true > true > false > false > false > true
Example 2:
<script> // 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); </script> |
Output:
> true > false > "GEEKSFORGEEKS"
Supported Browsers: The browsers supported by JavaScript in operator are listed below:
- Google Chrome
- Firefox
- Opera
- Safari
- Edge
- Internet Explorer