From b1ae728bee96f2a854b7d971a4025a058049f9e3 Mon Sep 17 00:00:00 2001
From: ayush <ayush.tripathi@groww.in>
Date: Thu, 6 Oct 2022 18:55:01 +0530
Subject: [PATCH] fix type narrowing issue in isEmpty function

close #129
---
 packages/ella/src/general/index.ts     |  7 +++++--
 packages/ella/src/utils/types/index.ts | 18 ++++++++++++++++++
 2 files changed, 23 insertions(+), 2 deletions(-)

diff --git a/packages/ella/src/general/index.ts b/packages/ella/src/general/index.ts
index 8324063b..852688a9 100644
--- a/packages/ella/src/general/index.ts
+++ b/packages/ella/src/general/index.ts
@@ -5,9 +5,11 @@
 import { dispatchCustomEvent } from '../dom';
 import { CUSTOM_EVENTS } from '../utils/constants';
 import {
+  Empty,
   GenericArguments,
   GenericFunction,
   MultiLevelObject,
+  PickEmptyType,
   SingleLevelObject,
   TabsData
 } from '../utils/types';
@@ -27,7 +29,8 @@ export { default as isEqual } from 'lodash.isequal';
  * }
  * ```
  */
-export function isEmpty(data: any) {
+export function isEmpty<T extends any>(data: T | Empty): data is PickEmptyType<T> {
+
   try {
     if (data === null || data === undefined || typeof data === 'undefined') {
       return true;
@@ -38,7 +41,7 @@ export function isEmpty(data: any) {
     switch (dataType) {
 
       case 'string':
-        if (data.trim() === '' || data === 'null' || data === null) {
+        if ((data as string).trim() === '' || (data as string) === 'null' || data === null) {
           return true;
         }
 
diff --git a/packages/ella/src/utils/types/index.ts b/packages/ella/src/utils/types/index.ts
index e9f3ccb1..0b27d315 100644
--- a/packages/ella/src/utils/types/index.ts
+++ b/packages/ella/src/utils/types/index.ts
@@ -66,3 +66,21 @@ export type TabsData = {
   searchId: string;
   [key:string]: unknown;
 };
+
+
+// isEmpty function
+
+export type AllowedValueType = string | number | Array<any> | object | null | undefined | Symbol;
+
+export type Empty =
+  | never[]
+  | Record<keyof any, never>
+  | ''
+  | null
+  | undefined
+  | never;
+
+export type PickEmptyType<T> =
+      T extends AllowedValueType
+        ? Empty
+        : T;