fix: target es2018 to support node 10+

examples/personal-site/tsconfig.json

@@ -5,8 +5,8 @@
         "moduleResolution": "node",
         "jsx": "react",
         "jsxFactory": "createElement",
-        "target": "ES2019",
+        "target": "ES2018",
-        "lib": ["ES2019"],
+        "lib": ["ES2018"],
         "strict": true,
         "noUnusedLocals": true,
         "noUnusedParameters": true,

package-lock.json

@@ -62,9 +62,9 @@
             "dev": true
         },
         "@types/node": {
-            "version": "12.12.38",
+            "version": "10.17.24",
-            "resolved": "https://registry.npmjs.org/@types/node/-/node-12.12.38.tgz",
+            "resolved": "https://registry.npmjs.org/@types/node/-/node-10.17.24.tgz",
-            "integrity": "sha512-75eLjX0pFuTcUXnnWmALMzzkYorjND0ezNEycaKesbUBg9eGZp4GHPuDmkRc4mQQvIpe29zrzATNRA6hkYqwmA==",
+            "integrity": "sha512-5SCfvCxV74kzR3uWgTYiGxrd69TbT1I6+cMx1A5kEly/IVveJBimtAMlXiEyVFn5DvUFewQWxOOiJhlxeQwxgA==",
             "dev": true
         },
         "@types/ws": {

package.json

@@ -8,7 +8,7 @@
     },
     "license": "MPL-2.0",
     "engines": {
-        "node": ">=12"
+        "node": ">=10"
     },
     "main": "dist/index.js",
     "types": "types.d.ts",
@@ -29,7 +29,7 @@
         "test": "ts-node --project=test/tsconfig.json test/run-tests.ts"
     },
     "devDependencies": {
-        "@types/node": "~12",
+        "@types/node": "~10",
         "@types/ws": "^7.2.4",
         "@typescript-eslint/eslint-plugin": "^3.0.2",
         "@typescript-eslint/parser": "^3.0.2",

src/create-element.ts

@@ -5,6 +5,7 @@
 
 import { Component, Element, HTMLElement } from "./component";
 import { HTMLAttributes } from "./jsx";
+import { flatDeep } from "./utils";
 
 /**
  * Create an HTMLElement from a custom Component.
@@ -42,7 +43,7 @@ export function createElement(
     ...children: Element[]
 ): HTMLElement {
     // Flatten the children array so we can accept arrays as children.
-    const normalizedChildren = children.flat();
+    const normalizedChildren = flatDeep(children);
     if (type instanceof Function) {
         return type({ ...props, children: normalizedChildren });
     }

src/utils.ts

@@ -48,3 +48,26 @@ export const purgeModuleAndDepsFromCache = (modName: string): void => {
     }
     delete require.cache[modPath];
 };
+
+export type Flattenable<T> = Array<T | Flattenable<T>>;
+
+const flatDeepRec = <T>(arr: Flattenable<T>, d: number): T[] => {
+    if (d <= 0) {
+        return arr.slice() as T[];
+    }
+
+    let acc = [] as T[];
+    for (const val of arr) {
+        acc = acc.concat(Array.isArray(val) ? flatDeepRec(arr, d - 1) : val);
+    }
+    return acc;
+};
+
+/**
+ * Flatten an arbitrarily-deeply nested array into a flat array.
+ *
+ * @param arr Array to flatten.
+ *
+ * @return Flattened array.
+ */
+export const flatDeep = <T>(arr: Flattenable<T>): T[] => flatDeepRec(arr, 1);

tsconfig-base.json

@@ -3,8 +3,8 @@
         "esModuleInterop": true,
         "module": "CommonJS",
         "moduleResolution": "node",
-        "target": "ES2019",
+        "target": "ES2018",
-        "lib": ["ES2019"],
+        "lib": ["ES2018"],
         "strict": true,
         "noUnusedLocals": true,
         "noUnusedParameters": true,