Example 1: Check if Key Exists in Object Using in Operator
// program to check if a key exists
const person = {
id: 1,
name: 'John',
age: 23
}
// check if key exists
const hasKey = 'name' in person;
if(hasKey) {
console.log('The key exists.');
}
else {
console.log('The key does not exist.');
}
Output
The key exists.
In the above program, the in operator is used to check if a key exists in an object. The in operator returns true if the specified key is in the object, otherwise it returns false.
Example 2: Check if Key Exists in Object Using hasOwnProperty()
// program to check if a key exists
const person = {
id: 1,
name: 'John',
age: 23
}
//check if key exists
const hasKey = person.hasOwnProperty('name');
if(hasKey) {
console.log('The key exists.');
}
else {
console.log('The key does not exist.');
}
Output
The key exists.
In the above program, the hasOwnProperty() method is used to check if a key exists in an object. The hasOwnProperty() method returns true if the specified key is in the object, otherwise it returns false.
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