Add prebuild script and tsconfig to generate declarations (#125)

* Add prebuild script and tsconfig to generate declarations

* Add 'types' key to package.json

package.json

@@ -7,6 +7,7 @@
   "main": "dist/Shepherd.js",
   "module": "dist/Shepherd.es.js",
   "jsnext:main": "dist/Shepherd.es.js",
+  "types": "dist/index.d.ts",
   "homepage": "https://shipshapecode.github.io/react-shepherd/",
   "engines": {
     "node": ">=8",
@@ -15,6 +16,7 @@
   "scripts": {
     "test": "cross-env CI=1 react-scripts test",
     "test:watch": "react-scripts test",
+    "prebuild": "tsc --project ./tsconfig-declarations.json",
     "build": "rollup -c",
     "start": "rollup -c -w",
     "prepare": "yarn run build",

src/index.tsx

@@ -34,7 +34,9 @@ const addSteps = (steps: Array<Step> | Array<Step.StepOptions>, tour: Tour) => {
       step.buttons = buttons.map((button: ShepherdStepWithType) => {
         const { type, classes, text, action } = button;
         return {
-          action: action || tour[type],
+          // TypeScript doesn't have great support for dynamic method calls with
+          // bracket notation, so we use the `any` escape hatch
+          action: action || (tour as any)[type!],
           classes,
           text,
           type

tsconfig-declarations.json

@@ -0,0 +1,9 @@
+{
+  "extends": "./tsconfig.json",
+  "compilerOptions": {
+    "isolatedModules": false,
+    "noEmit": false,
+    "declaration": true,
+    "emitDeclarationOnly": true
+  }
+}