"Cannot calculate square root of a negative number"

Error: "Invalid number"

3

NaN

{ id: '123', name: 'Alice', email: '[email protected]' }

Error: "User ID is required"

undefined

Error: "User not found"

1,2,3,4

3,4

1,2,3

1,3,4

1

1, 2

2

1,3

Error

1

1, 2

2

defining multiple classes in the same file;

using multiple constructors in a class;

allowing methods to be overridden in subclasses;

creating multiple instances of a class;

using the _ (underscore) convention

JavaScript does not support private fields

prefixing the field name with #

using the private keyword

super();

call.Parent();

this.constructor();

parent();

50

Error

15

undefined

declaring all variables globally;

using getters and setters;

avoiding functions inside objects;

using private access modifiers;