Understanding the distinction between deleting and nullifying in JavaScript

var obj = {type: "beetle", price : "xxx", popular: "yes" ,.... };

If I want to remove all the properties from obj, what is the correct way to do it?

  • Should I use

    delete obj.type; delete obj.price; delete obj.popular
    ... and so on.

  • Or should I set obj = null;?

  • Or will letting obj go out of scope automatically delete the properties?

Answer №1

According to MDN, the JavaScript delete operator is used to remove a property from an object, and if there are no more references to that property, it will be automatically released.

It's important to note that setting an object to null is a completely different concept than using the delete operator. Additionally, trying to access a non-existent property like 's' will not work because it does not belong to any object.

Answer №2

If you assign a property the value of null, it remains in existence without any defined value. However, if you delete the property entirely, it will cease to exist within the context.

Answer №3

There is a distinct difference between deleting the car property of object s and assigning it as null. Even though deleting the property leaves s as an empty object, it still retains its status as an object which can access certain methods like s.toString() and s.hasOwnProperty(propname). On the other hand, assigning null to s turns it into a primitive value with limited capabilities - you cannot call any methods on it. Additionally, an empty object like {} evaluates to true when coerced to Boolean, while null evaluates to false.

Therefore, it is clear that these values behave in very different ways.

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