fix: add function

src/function/get.ts

@@ -0,0 +1,21 @@
+import type { Dictionary, PropertyPath } from '../type';
+import { isDef } from '../is';
+
+function get<T>(
+  entity: Dictionary<T> | null | undefined,
+  ...paths: PropertyPath[]
+): T[keyof T] | undefined {
+  let current: any = entity;
+
+  for (let i = 0; i < paths.length; i += 1) {
+    if (isDef(current)) {
+      return undefined;
+    }
+
+    current = current[paths[i] as keyof T];
+  }
+
+  return current;
+}
+
+export default get;

src/function/index.ts

@@ -0,0 +1,2 @@
+export { default as set } from './set';
+export { default as get } from './get';

src/function/set.ts

@@ -0,0 +1,28 @@
+import { PropertyPath } from '../type';
+
+function set<Entity = any, Output = Entity, Value = any>(
+  entity: Entity,
+  paths: PropertyPath[],
+  value: Value,
+): Output {
+  if (!paths.length) {
+    return (value as unknown) as Output;
+  }
+
+  const [path, ...restPath] = paths;
+
+  let clone: Output;
+  if (!entity && typeof path === 'number') {
+    clone = ([] as unknown) as Output;
+  } else if (Array.isArray(entity)) {
+    clone = ([...entity] as unknown) as Output;
+  } else {
+    clone = ({ ...entity } as unknown) as Output;
+  }
+
+  clone[path as string] = set(clone[path as string], restPath, value);
+
+  return clone;
+}
+
+export default set;

src/index.ts

@@ -15,6 +15,7 @@ export * from './dom';
 export * from './bom';
 export * from './date';
 export * from './things';
+export * from './function';
 export * from './regex_constant';
 
 export { default as noop } from './noop';

src/type.d.ts

@@ -0,0 +1,13 @@
+export type Many<T> = T | ReadonlyArray<T>;
+
+export type PropertyName = string | number | symbol;
+
+export type PropertyPath = Many<PropertyName>;
+
+export interface Dictionary<T> {
+  [index: string]: T;
+}
+
+export interface NumericDictionary<T> {
+  [index: string]: T;
+}