Property setter functions that silently ignore their parameter make code hard to understand and could indicate an underlying bug.

If the property is meant to be immutable, the setter should throw an exception to flag any mutation attempt.

The following example shows a constructor function Point that uses property accessors on x and y to ensure that they are only set to integer values. However, the setter for y contains a typo: it erroneously sets y to _x (which is unbound at this point), not to its parameter _y.

Clearly, the example should be fixed like this:

Mozilla Developer Network: Property setters.