Delete operator in JavaScript

In JavaScript, the delete operator is used to remove properties from objects. It allows you to remove both own properties of an object and properties inherited from its prototype chain. However, there are some important considerations and limitations when using the delete operator. Let's investigate into the details with examples:

Deleting Own Properties

You can use the delete operator to remove properties directly attached to an object:

const person = { name: "Bill", age: 30, }; delete person.age; console.log(person); // Output: { name: "Bill" }

In this example, the age property is removed from the person object using delete.

Deleting Inherited Properties

The delete operator can also remove properties inherited from the object's prototype:

function Person(name) { = name; } Person.prototype.sayHello = function() { console.log(`Hello, my name is ${}.`); }; const bill = new Person("Bill"); delete bill.sayHello; bill.sayHello(); // Error: sayHello is not a function

In this case, the sayHello method is removed from the bill object, causing an error when trying to call it.

Limitations and Considerations

  1. Cannot Delete Variables or Functions: The delete operator cannot remove variables or functions declared with var, let, const, or function declarations.
  2. Non-configurable Properties: If a property is marked as non-configurable (using Object.defineProperty or similar methods), the delete operator will have no effect.
  3. Array Elements: The delete operator can be used to remove elements from arrays, but it will leave an empty slot instead of reindexing the array.
const numbers = [1, 2, 3, 4]; delete numbers[2]; console.log(numbers); // Output: [1, 2, <1 empty slot>, 4]
  1. Use with Caution: The delete operator can lead to unexpected behavior, especially when dealing with prototype chains and unintended property removals.
  2. Memory Management: While the delete operator removes properties, it does not free up memory associated with the object. Modern JavaScript engines handle memory management, and manual property deletion is rarely necessary for memory optimization.


The delete operator in JavaScript allows you to remove properties from objects, both own and inherited. However, due to its limitations and potential for unexpected behavior, it should be used with caution, and alternative approaches should be considered when managing properties and data structures.