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I am giving a try to Webpack, and am giving a try to the instructions in this tutorial, give or take a few custom things.
This is simple code, really, but I'm quite puzzled about this error, and feel this is something silly that I missed.
I defined two ES6 classes, each corresponding to a Handlebars template, and my app's entrypoint is supposed to replace the placeholder HTML in the index file by their contents:
Entrypoint:
import './bloj.less'
// If we have a link, render the Button component on it
if (document.querySelectorAll('a').length) {
require.ensure([], () => {
const Button = require('./Components/Button.js');
const button = new Button('9gag.com');
button.render('a');
}, 'button');
}
// If we have a title, render the Header component on it
if (document.querySelectorAll('h1').length) {
require.ensure([], () => {
const Header = require('./Components/Header.js');
new Header().render('h1');
}, 'header');
}
Index:
<!DOCTYPE html>
<html>
<head>
</head>
<body>
<h1>My title</h1>
<a>Click me</a>
<script src="build/bloj.js"></script>
</body>
</html>
Button:
import $ from 'jquery';
import './Button.less';
export default class Button {
constructor(link) {
this.link = link;
}
onClick(event) {
event.preventDefault();
alert(this.link);
}
render(node) {
const text = $(node).text();
var compiled = require('./Button.hbs');
// Render our button
$(node).html(
compiled({"text": text, "link": this.link})
);
// Attach our listeners
$('.button').click(this.onClick.bind(this));
}
}
Header:
import $ from 'jquery';
import './Header.less';
export default class Header {
render(node) {
const text = $(node).text();
var compiled = require('./Header.hbs');
// Render the header
$(node).html(
compiled({"text": text})
);
}
}
Sadly, it does not work, and I get both these errors when displaying the page:
Uncaught TypeError: Header is not a constructor
Uncaught TypeError: Button is not a constructor
What could I be missing?
Here is my webpack configuration:
var path = require('path');
var webpack = require('webpack');
var CleanPlugin = require('clean-webpack-plugin');
var ExtractPlugin = require('extract-text-webpack-plugin');
var production = process.env.NODE_ENV === 'production';
var appName = 'bloj';
var entryPoint = './src/bloj.js';
var outputDir = './build/';
var publicDir = './build/';
// ************************************************************************** //
var plugins = [
//new ExtractPlugin(appName + '.css', {allChunks: true}),
new CleanPlugin(outputDir),
new webpack.optimize.CommonsChunkPlugin({
name: 'main',
children: true,
minChunks: 2
})
];
if (production) {
plugins = plugins.concat([
new webpack.optimize.DedupePlugin(),
new webpack.optimize.OccurenceOrderPlugin(),
new webpack.optimize.MinChunkSizePlugin({
minChunkSize: 51200 // 50ko
}),
new webpack.optimize.UglifyJsPlugin({
mangle: true,
compress: {
warnings: false // Suppress uglification warnings
}
}),
new webpack.DefinePlugin({
__SERVER__: false,
__DEVELOPMENT__: false,
__DEVTOOLS__: false,
'process.env': {
BABEL_ENV: JSON.stringify(process.env.NODE_ENV)
}
})
]);
}
module.exports = {
entry: entryPoint,
output: {
path: outputDir,
filename: appName + '.js',
chunkFilename: '[name].js',
publicPath: publicDir
},
debug: !production,
devtool: production ? false : 'eval',
module: {
loaders: [
{
test: /\.js/,
loader: "babel",
include: path.resolve(__dirname, 'src'),
query: {
presets: ['es2015']
}
},
{
test: /\.less/,
//loader: ExtractPlugin.extract('style', 'css!less')
loader: "style!css!less"
},
{
test: /\.html/,
loader: 'html'
},
{
test: /\.hbs/,
loader: "handlebars-template-loader"
}
]
},
plugins: plugins,
node: {
fs: "empty" // Avoids Handlebars error messages
}
};
555
What could I be missing?
Babel assigns default exports to the default property. So if you use require to import ES6 modules, you need to access the default property:
const Button = require('./Components/Button.js').default;
I realize that you already have an answer. However I had a similar issue to which I found an answer. Starting my own question and answering it seems weird. So I'm just going to leave this here.
I had the same error as you got. However, I managed to solve it by changing my
export default {Class}
to
export default Class
I don't know why I wrapped the Class in an object but I remember having seen it somewhere so I just started using it.
So instead of the default returning a Class it returned an object like this {Class: Class}.
This is completely valid yet it will break webpack+babel.
EDIT: I've since come to know why this probably breaks babel+webpack. The export default is meant to only have 1 export. A javascript-object can contain many properties. Which means it can have more than 1 export. (See: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/export).
For multiple exports use: export {definition1, definition2}.
Use-case: I've used this in a situation where I've created a library which exported different types of an editor (while the underlying code was the same, the appearance of the editor changes depending on which export you use).
21
You can just put export var __useDefault = true; just after exporting your Class.
export default class Header {
...
}
export var __useDefault = true;
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