Clean Code in JavaScript

The delete operator

The delete operator can be used to remove properties from objects, as such its only operand usually takes the form of a property accessor, like so:

delete object.property;delete object[property];

Only properties that are deemed configurable can be deleted in this manner. All properties added conventionally are, by default, configurable and can, therefore, be deleted:

const foo = { baz: 123; };foo.baz;        // => 123delete foo.baz; // => truefoo.baz;        // => undefined'baz' in foo;   // => undefined

However, if the property has been added via defineProperty with configurable set to false, then it'll not be deletable:

const foo = {};Object.defineProperty(foo, 'baz', {  value: 123,  configurable: false});foo.baz; // => 123delete foo.baz; ...