The in operator is a built-in operator in JavaScript, used to check whether a specific property exists in an object. It returns Boolean 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 shown above and described in detail below:
- prop: This parameter holds the string 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 test() { // Illustration of in operator const array = ['Codes', 'for', 'Config'] // 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); } test(); </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 = ['CodeConfig', 'CodeConfig.in', 'Codes', 'Codes1'] // 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('CodeConfig.in' in array) // output of the Array property console.log('length' in array) </script> |
Output:
true true false false false true
Example 3: Let’s check the use of the in operator with the help of example in JavaScript.
JavaScript
<script> // Illustration of in operator const object = { val1: 'CodeConfig.in', 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 = 'CodeConfig.in'; } console.log(object.val1); </script> |
Output:
true
false
"CodeConfig.in"
Supported Browsers: The browsers supported by JavaScript in operator are listed below:
- Google Chrome
- Firefox
- Opera
- Safari
- Edge
- Internet Explorer
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