Add TypeScript definition and require Node.js 6

.travis.yml

@@ -1,5 +1,5 @@
 language: node_js
 node_js:
+  - '10'
   - '8'
   - '6'
-  - '4'

index.d.ts

@@ -0,0 +1,54 @@
+type Replacer = (key: string, value: any) => void;
+
+interface Options {
+	indent?: string | number | null;
+	detectIndent?: boolean;
+	sortKeys?: boolean | ((a: string, b: string) => number);
+	replacer?: Replacer | Array<number | string> | null;
+	mode?: number;
+}
+
+/**
+ * Stringify and write JSON to a file atomically
+ *
+ * Creates directories for you as needed.
+ *
+ * @param {string} filepath Filepath
+ * @param {any} data Data
+ * @param {object} [options] Optional parameters
+ * @param {string|number|null} [options.indent='\t'] Indentation as a string or number of spaces. Pass in null for no formatting.
+ * @param {boolean} [options.detectIndent=false] Detect indentation automatically if the file exists.
+ * @param {boolean|function} [options.sortKeys=false] Sort the keys recursively. Optionally pass in a compare function.
+ * @param {function|Array<number|string>|null} [options.replacer] Passed into JSON.stringify.
+ * @param {number} [options.mode=0o666] Mode used when writing the file.
+ * @returns {void}
+ * @example
+ * const writeJsonFile = require('write-json-file');
+ *
+ * writeJsonFile.sync('foo.json', {foo: true});
+ * console.log('done');
+ */
+export function sync(filepath: string, data: any, options?: Options): void;
+
+/**
+ * Stringify and write JSON to a file atomically
+ *
+ * Creates directories for you as needed.
+ *
+ * @param {string} filepath Filepath
+ * @param {any} data Data
+ * @param {object} [options] Optional parameters
+ * @param {string|number|null} [options.indent='\t'] Indentation as a string or number of spaces. Pass in null for no formatting.
+ * @param {boolean} [options.detectIndent=false] Detect indentation automatically if the file exists.
+ * @param {boolean|function} [options.sortKeys=false] Sort the keys recursively. Optionally pass in a compare function.
+ * @param {function|Array<number|string>|null} [options.replacer] Passed into JSON.stringify.
+ * @param {number} [options.mode=0o666] Mode used when writing the file.
+ * @returns {Promise<void>}
+ * @example
+ * const writeJsonFile = require('write-json-file');
+ *
+ * writeJsonFile('foo.json', {foo: true}).then(() => {
+ * 	console.log('done');
+ * });
+ */
+export default function writeJsonFile(filepath: string, data: any, options?: Options): Promise<void>;

index.js

@@ -44,7 +44,7 @@ const main = (fp, data, opts) => {
 };
 
 const mainSync = (fp, data, opts) => {
-	let indent = opts.indent;
+	let {indent} = opts;
 
 	if (opts.detectIndent) {
 		try {
@@ -67,6 +67,12 @@ module.exports = (fp, data, opts) => {
 		.then(() => init(main, fp, data, opts));
 };
 
+// Support for Typescript default export
+module.exports.default = (fp, data, opts) => {
+	return makeDir(path.dirname(fp), {fs})
+		.then(() => init(main, fp, data, opts));
+};
+
 module.exports.sync = (fp, data, opts) => {
 	makeDir.sync(path.dirname(fp), {fs});
 	init(mainSync, fp, data, opts);

package.json

@@ -10,14 +10,16 @@
     "url": "sindresorhus.com"
   },
   "engines": {
-    "node": ">=4"
+    "node": ">=6"
   },
   "scripts": {
     "test": "xo && ava"
   },
   "files": [
-    "index.js"
+    "index.js",
+    "index.d.ts"
   ],
+  "types": "index.d.ts",
   "keywords": [
     "write",
     "json",