You have an object with several properties and you want to remove some of these properties before using the object further.
let person = { firstName: "John", lastName: "Doe", gender: "Male", age: 34 }; const json = JSON.stringify(person); console.log(json); // => {"firstName":"John","lastName":"Doe","gender":"Male","age":34} // What can we do if we don't want the `age` property in the JSON string? -->
Here the JSON string also contains the age
property. However, you will be sending the string over the network, and the server on the other end won’t be using the age
property. So you want to remove the age
property from the person
object before converting it to a JSON string.
You can use the delete
operator, which is simpler, or object destructuring, which can remove more than a single property at a time.
delete
operatorUse the delete
operator to remove a property from an object.
let person = { firstName: "John", lastName: "Doe", gender: "Male", age: 34 }; // Delete the age property first delete person.age; let json = JSON.stringify(person); console.log(json);
The delete
operator will return if it was successful and always returns true
- even when a property does not exist. The call will only return false
when a property is non-configurable - which is the case for properties on built-in objects like the length
of an Array
.
The delete
operator can only remove one property per call. So if you want to delete the age
and gender
properties, then you have to make two delete
calls. As an alternative, you can use object destructuring to remove multiple properties with one call.
const person = { firstName: "John", lastName: "Doe", gender: "Male", age: 34 }; // Destructure the age and gender const {age, gender, ...personTrimmed} = person; const json = JSON.stringify(personTrimmed); console.log(json);
Note that destructuring is significantly slower than the delete
operator because it makes a new object copy from the original object. Destructuring is also not supported by any versions of IE.