diff --git a/js/index.d.ts b/js/index.d.ts
new file mode 100644
index 00000000..b65248e3
--- /dev/null
+++ b/js/index.d.ts
@@ -0,0 +1,45 @@
+interface ExecOptions {
+    cwd?: string,
+    env?: { [key: string]: string }
+}
+
+interface ExecResults {
+    errno: number,
+    stdout: string,
+    stderr: string
+}
+
+declare function exec(command: string): Promise<ExecResults>;
+declare function exec(command: string, options: ExecOptions): Promise<ExecResults>;
+
+interface SpawnOptions {
+    cwd?: string,
+    env?: { [key: string]: string }
+}
+
+interface Stdio {
+    on(event: 'data', callback: (data: string) => void)
+}
+
+interface ChildProcess {
+    stdout: Stdio,
+    stderr: Stdio,
+    on(event: 'exit', callback: (code: number) => void)
+    on(event: 'error', callback: (err: any) => void)
+}
+
+declare function spawn(command: string): ChildProcess;
+declare function spawn(command: string, args: string[]): ChildProcess;
+declare function spawn(command: string, options: SpawnOptions): ChildProcess;
+declare function spawn(command: string, args: string[], options: SpawnOptions): ChildProcess;
+
+declare function fullScreen(isFullScreen: boolean);
+
+declare function toast(message: string);
+
+export {
+    exec,
+    spawn,
+    fullScreen,
+    toast
+}
diff --git a/js/index.js b/js/index.js
index 7d547425..4b64e9c4 100644
--- a/js/index.js
+++ b/js/index.js
@@ -71,7 +71,7 @@ function Stdio() {
   export function spawn(command, args, options) {
     if (typeof args === "undefined") {
       args = [];
-    } else if (typeof args === "object") {
+    } else if (!(args instanceof Array)) {
         // allow for (command, options) signature
         options = args;
     }