transpile sources in build step (#3214)

- update contribution guide

Author: HackbrettXXX

.babelrc

@@ -0,0 +1,4 @@
+{
+  "extends": "./.babelrc.json",
+  "plugins": ["@babel/plugin-transform-runtime"]
+}

.babelrc.esm.json

@@ -0,0 +1,4 @@
+{
+  "presets": [["@babel/env"]],
+  "exclude": ["node_modules/**"]
+}

.babelrc.json

@@ -48,9 +48,10 @@ preparing a pull request please follow these guidelines:
 - Make sure to cover new features or bugs with test cases. Test cases should be as small as possible.
 - Make sure to follow the PDF specification. JsPDF currently implements part of the PDF 1.3 specification.
 - Make sure all tests are green before committing (`npm run test-local`)
-- Use only es5-compatible code in the `src` folder (except for import/export statements). The sources are currently
-  not babeled. When using newer EcmaScript or Browser APIs make sure the required polyfills are listed in
-  `src/polyfills.js`.
+- You may now (and should!) use modern JavaScript everywhere. The build step will transpile it. Most of the sources
+  are still in ES5, but all new code should be written in ES6+.
+- When using newer EcmaScript or Browser APIs make sure the required polyfills are listed in
+  `src/polyfills.js`. At the moment, the library must still run in IE11!
 - Run `npm run prettier` before committing.
 - Don't update the files in `dist` in regular pull requests. These are usually only updated when creating a new release.
 - For the commit message, follow these guidelines:

CONTRIBUTING.md

@@ -23,6 +23,7 @@
     "url": "https://github.com/MrRio/jsPDF.git"
   },
   "dependencies": {
+    "@babel/runtime": "^7.14.0",
     "atob": "^2.1.2",
     "btoa": "^1.2.1",
     "fflate": "^0.4.8"
@@ -35,15 +36,15 @@
   },
   "devDependencies": {
     "@babel/core": "^7.10.4",
-    "@babel/plugin-external-helpers": "^7.10.4",
+    "@babel/plugin-transform-runtime": "^7.14.5",
     "@babel/preset-env": "^7.10.4",
+    "@rollup/plugin-babel": "^5.3.0",
     "@rollup/plugin-replace": "^2.3.3",
     "@rollup/plugin-typescript": "^8.0.0",
     "@types/jasmine": "^3.5.11",
     "@types/node": "^14.0.18",
     "@typescript-eslint/eslint-plugin": "^3.6.0",
     "@typescript-eslint/parser": "^3.6.0",
-    "babel-plugin-rewire-exports": "^2.2.0",
     "chalk": "^4.1.0",
     "codeclimate-test-reporter": "^0.5.1",
     "core-js": "^3.6.0",
@@ -67,7 +68,7 @@
     "karma-jasmine": "3.3.1",
     "karma-jasmine-matchers": "4.0.2",
     "karma-mocha-reporter": "2.2.5",
-    "karma-rollup-preprocessor": "^7.0.5",
+    "karma-rollup-preprocessor": "^7.0.7",
     "karma-sauce-launcher": "4.1.5",
     "karma-typescript": "^5.0.3",
     "karma-verbose-reporter": "0.0.6",
@@ -108,5 +109,9 @@
     "lint": "prettier --check \"*.{js,ts,md,css,json}\" \"{spec,examples,src,types}/**/*.{js,ts,md,css,json}\"",
     "pregenerate-docs": "node deletedocs.js",
     "generate-docs": "jsdoc -c jsdoc.json --readme README.md"
-  }
+  },
+  "browserslist": [
+    "last 2 versions",
+    "IE 11"
+  ]
 }

package-lock.json

@@ -1,4 +1,5 @@
 import { terser } from "rollup-plugin-terser";
+import { babel } from "@rollup/plugin-babel";
 import RollupPluginPreprocess from "rollup-plugin-preprocess";
 import resolve from "rollup-plugin-node-resolve";
 import commonjs from "rollup-plugin-commonjs";
@@ -67,6 +68,7 @@ const umd = {
     commonjs(),
     RollupPluginPreprocess({ context: { MODULE_FORMAT: "umd" } }),
     replaceVersion(),
+    babel({ babelHelpers: "bundled", configFile: "./.babelrc.json" }),
     licenseBanner()
   ]
 };
@@ -94,6 +96,7 @@ const es = {
     resolve(),
     RollupPluginPreprocess({ context: { MODULE_FORMAT: "es" } }),
     replaceVersion(),
+    babel({ babelHelpers: "runtime", configFile: "./.babelrc.esm.json" }),
     licenseBanner()
   ]
 };

package.json

@@ -1,5 +1,6 @@
 const karmaConfig = require("../../karma.common.conf.js");
 const resolve = require("rollup-plugin-node-resolve");
+const commonjs = require("rollup-plugin-commonjs");
 
 module.exports = config => {
   config.set({
@@ -51,7 +52,7 @@ module.exports = config => {
     },
 
     rollupPreprocessor: {
-      plugins: [resolve()],
+      plugins: [resolve(), commonjs()],
       output: {
         format: "iife",
         name: "jspdf",

rollup.config.js

@@ -2,6 +2,7 @@ const karmaConfig = require("../../karma.common.conf.js");
 const typescript = require("@rollup/plugin-typescript");
 const replace = require("@rollup/plugin-replace");
 const resolve = require("rollup-plugin-node-resolve");
+const commonjs = require("rollup-plugin-commonjs");
 
 module.exports = config => {
   config.set({
@@ -46,7 +47,8 @@ module.exports = config => {
           delimiters: ["", ""],
           '"jspdf"': '"../../../dist/jspdf.es.js"'
         }),
-        resolve()
+        resolve(),
+        commonjs()
       ],
       output: {
         format: "iife",