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 a 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 is to be checked whether it contains the prop.
Return value: This method returns a boolean value:
- 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.
Example 1: Below is an example of the in-operator.
Javascript
<script> function gfg() { // Illustration of in operator const array = ['neveropen', 'for', 'neveropen'] // 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(); </script> |
Output:
true false true
Example 2: This example shows the use of the in operator in Javascript.
Javascript
<script> // Illustration of in operator const array = ['neveropen', 'neveropenfor', 'neveropen', 'neveropen1'] // 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('neveropen' in array) // output of the Array property console.log('length' in array) </script> |
Output:
true true false false false true
Example 3: This example shows the use of the in operator in Javascript.
Javascript
<script> // Illustration of in operator const object = { val1: 'Geeksforneveropen', 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"
We have a complete list of Javascript Operators, to check those please go through the Javascript Operators Complete Reference article.
Supported Browsers: The browsers supported by JavaScript in operator are listed below:
- Google Chrome
- Firefox
- Opera
- Safari
- Edge
- Internet Explorer
