Preparing the project for TypeScript (#10595)

* Add Typescript to the build
* Converts the `helpers.core` to Typescript as an example
* Converts the `core.element` to Typescript

Author: dangreen

.eslintrc.yml

@@ -36,3 +36,24 @@ rules:
   es/no-regexp-s-flag: "error"
   es/no-regexp-unicode-property-escapes: "error"
   es/no-dynamic-import: "off"
+
+overrides:
+  - files: ['**/*.ts']
+    parser: '@typescript-eslint/parser'
+    plugins:
+      - '@typescript-eslint'
+    extends:
+      - chartjs
+      - plugin:@typescript-eslint/recommended
+
+    rules:
+      # Replace stock eslint rules with typescript-eslint equivalents for proper
+      # TypeScript support.
+      indent: "off"
+      "@typescript-eslint/indent": ["error", 2]
+      no-use-before-define: "off"
+      '@typescript-eslint/no-use-before-define': "error"
+      no-shadow: "off"
+      '@typescript-eslint/no-shadow': "error"
+      space-before-function-paren: "off"
+      '@typescript-eslint/space-before-function-paren': [2, never]

.size-limit.cjs

@@ -7,7 +7,7 @@ function modifyWebpackConfig(config) {
 module.exports = [
   {
     path: 'dist/chart.js',
-    limit: '75 KB',
+    limit: '77 KB',
     webpack: false,
     running: false
   },

auto/auto.d.ts

@@ -1,4 +1,4 @@
-import {Chart} from '../types';
+import {Chart} from '../dist/types';
 
-export * from '../types';
+export * from '../dist/types';
 export default Chart;

docs/developers/charts.md

@@ -130,8 +130,8 @@ When adding a new chart type, `ChartTypeRegistry` must contains the declarations
 
 For example, to provide typings for a new chart type that extends from a bubble chart, you would add a `.d.ts` containing:
 
-```ts
-import { ChartTypeRegistry } from 'chart.js'
+```typescript
+import { ChartTypeRegistry } from 'chart.js';
 
 declare module 'chart.js' {
     interface ChartTypeRegistry {

helpers/helpers.d.ts

@@ -1 +1 @@
-export * from '../types/helpers';
+export * from '../dist/helpers/types';

karma.conf.cjs

@@ -27,11 +27,9 @@ module.exports = async function(karma) {
   }
 
   if (args.coverage) {
-    build.plugins = [
-      json(),
-      resolve(),
+    build.plugins.push(
       istanbul({exclude: ['node_modules/**/*.js', 'package.json']})
-    ];
+    );
   }
 
   karma.set({
@@ -92,14 +90,14 @@ module.exports = async function(karma) {
       'node_modules/moment-timezone/builds/moment-timezone-with-data.min.js',
       {pattern: 'test/index.js', watched: false},
       {pattern: 'test/BasicChartWebWorker.js', included: false},
-      {pattern: 'src/index.umd.js', watched: false},
+      {pattern: 'src/index.umd.ts', watched: false},
       'node_modules/chartjs-adapter-moment/dist/chartjs-adapter-moment.js',
       {pattern: specPattern}
     ],
 
     preprocessors: {
       'test/index.js': ['rollup'],
-      'src/index.umd.js': ['sources']
+      'src/index.umd.ts': ['sources']
     },
 
     rollupPreprocessor: {