Duplicate constructor in same class in JSX webpack build - reactjs

Question

I'm having an issue with some code I wrote that's utterly stumped me.
The main JSX tutorial available at the JSX Github Page has an example class called Point, which looks like:
class Point {
var x = 0;
var y = 0;
function constructor() {
}
function constructor(x : number, y : number) {
this.set(x, y);
}
function constructor(other : Point) {
this.set(other);
}
function set(x : number, y : number) : void {
this.x = x;
this.y = y;
}
function set(other : Point) : void {
this.set(other.x, other.y);
}
}
That class has a clear example of a multiple constructor types which I'm familiar from my C++ days. It even has a defined copy constructor, which I think is great.
However, if I got and create a similar class for use by me:
export default class MutableDataStore {
constructor() {
this.data = [];
this.settings = {};
}
//Copy constructor
constructor(other : MutableDataStore) {
this.data = other.data.slice();
this.settings = Object.assign({}, this.settings);
}
//...Other functions omitted
}
I get the following error in my webpack build:
ERROR in ./src/stores/helper-classes/mutabledatastore.jsx
Module build failed: SyntaxError: Duplicate constructor in the same class (8:1)
I'm completely stumped by this, since I can't find anything similar on the web about this, unless it seems to be a transient issue.
My webpack.config.js is:
var webpack = require("webpack");
var path = require("path");
var src = path.resolve(__dirname, "src");
var app = path.resolve(__dirname, "app");
var config = {
entry: src + "/index.jsx",
output: {
path: app,
filename: "javascript.js"
},
module: {
loaders: [{
include: src,
loader: "babel-loader"
}]
}
};
module.exports = config;
and my babel presets are es2015 and react.
Any help would be appreciated!

Answer 1

As loganfsmyth said in the comments, there can only be one constructor in an ES6 class. You can get the desired effect by either checking if other is set in the construct or by providing a default value for the parameter
export default class MutableDataStore {
constructor(other : MutableDataStore) {
this.data = other ? other.data.slice() : [];
this.settings = other ? Object.assign({}, other.settings) : {};
}
//...Other functions omitted
}
// or
export default class MutableDataStore {
constructor(other : MutableDataStore = { data: [], settings: {} }) {
this.data = other.data.slice();
this.settings = Object.assign({}, other.settings);
}
//...Other functions omitted
}
As a side not, I think you might have intended the copy constructor to copy the settings from other, not this.