Compile ES2015 classes to ES5
> Compile ES2015 classes to ES5
Built-in classes such as Date, Array, DOM etc cannot be properly subclassed
due to limitations in ES5 (for the es2015-classes plugin).
You can try to use babel-plugin-transform-builtin-extend based on Object.setPrototypeOf and Reflect.construct, but it also has some limitations.
``sh`
npm install --save-dev babel-plugin-transform-es2015-classes
.babelrc
`js
// without options
{
"plugins": ["transform-es2015-classes"]
}
// with options
{
"plugins": [
["transform-es2015-classes", {
"loose": true
}]
]
}
`
`sh`
babel --plugins transform-es2015-classes script.js
`javascript`
require("babel-core").transform("code", {
plugins: ["transform-es2015-classes"]
});
boolean, defaults to false.
#### Method enumerability
Please note that in loose mode class methods are enumerable. This is not in line
with the spec and you may run into issues.
#### Method assignment
Under loose mode, methods are defined on the class prototype with simple assignments
instead of being defined. This can result in the following not working:
`javascript
class Foo {
set bar() {
throw new Error("foo!");
}
}
class Bar extends Foo {
bar() {
// will throw an error when this method is defined
}
}
`
When Bar.prototype.foo is defined it triggers the setter on Foo`. This is a
case that is very unlikely to appear in production code however it's something
to keep in mind.