Writing Scripts in Nashorn - Scripting in Java: Integrating with Groovy and JavaScript - page 105

Deleting Properties of an Object
You can delete a configurable property of an object using the delete operator. Its syntax is:
delete property;
The following snippet of code creates an object with two properties x and y , iterator
over the properties, delete the property named x , and iterates over the properties again.
The second time, the property x and its value are not printed because it has been deleted:
// Create an object with two properties x and y
var point = {x:10, y:20};
for(var prop in point) {
printf("point[%s] = %d", prop, point[prop]);
}
// Delete property x from the point object
delete point.x;
print("After deleting x");
for(var prop in point) {
printf("point[%s] = %d", prop, point[prop]);
}
point[x] = 10
point[y] = 20
After deleting x
point[y] = 20
In strict mode, it is an error to delete to a property whose configurable attribute is
set to false . Deleting a nonconfigurable property in nonstrict mode has no effect.
Using a Constructor Function
A constructor function (or simply a constructor) is a function that is used with the new
operator to create an object. It is customary to start a constructor with an uppercase letter.
The following code creates a function named Person that is intended to be used as a
constructor:
// Declare a constructor named Person
function Person(fName, lName) {
this.fName = fName;
this.lName = lName;
this.fullName = function () {
return this.fName + " " + this.lName;
}
}