Why are class getters/setters non-enumerable?

/#!/JoePea joe at trusktr.io
Sat Oct 8 23:14:06 UTC 2016

I've ran into this bug due to non-enumerable accessors:

The problem is that Tween.js does not detect the getters/setters in a
for..in loop.

The solution I came up with is ugly, re-defining the descriptors to be
enumerable, as demonstrated below. Is there a better way? Why are accessors
non-enumerable when (to end user who use the properties to access values)
they are used in the exact same way that "properties" are? It seems that
they should be enumerable because whether or not they are "accessors" is
not the end user's concern, they merely access the "property"...

class XYZValues {
    constructor(x = 0, y = 0, z = 0) {
        this._x = x
        this._y = y
        this._z = z

    onChanged() {}

    set x(value) {
        this._x = value
    get x() { return this._x }

    set y(value) {
        this._y = value
    get y() { return this._y }

    set z(value) {
        this._z = value
    get z() { return this._z }

const xDesc = Object.getOwnPropertyDescriptor(XYZValues.prototype, 'x')
xDesc.enumerable = true
Object.defineProperty(XYZValues.prototype, 'x', xDesc)

const yDesc = Object.getOwnPropertyDescriptor(XYZValues.prototype, 'y')
yDesc.enumerable = true
Object.defineProperty(XYZValues.prototype, 'y', yDesc)

const zDesc = Object.getOwnPropertyDescriptor(XYZValues.prototype, 'z')
zDesc.enumerable = true
Object.defineProperty(XYZValues.prototype, 'z', zDesc)

export {XYZValues as default}

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