Chart.js/babel.config.json

{
  "presets": [
    "@babel/preset-env"
  ],
  "plugins": [
    "@babel/plugin-proposal-class-properties",
    "@babel/plugin-transform-object-assign"
  ],
  "env": {
    "es6": {
      "presets": [
        [
          "@babel/preset-env",
          {
            "targets": {
              "esmodules": true
            },
            "modules": false,
            "useBuiltIns": false
          }
        ]
      ],
      "plugins": [
        "@babel/plugin-proposal-class-properties"
      ]
    },
    "test": {
      "plugins": [
        "istanbul"
      ]
    }
  }
}