feat(assocPath): Add module assocPath

src/__tests__/assocPath.js

@@ -0,0 +1,13 @@
+import assocPath from '../assocPath';
+
+test('Core.assocPath', () => {
+  const origin = { a: 1, b: 2 };
+  const result = assocPath(['a'], 2, origin);
+  expect(result).toEqual({ a: 2, b: 2 });
+  expect(result).not.toBe(origin);
+
+  expect(assocPath(['a', 0], 1, { a: [0] })).toEqual({ a: [1] });
+  expect(assocPath(['a', 'b', 'c'], 'hidden', {})).toEqual({
+    a: { b: { c: 'hidden' } },
+  });
+});

src/assocPath.js

@@ -0,0 +1,36 @@
+import length from './length';
+import slice from './slice';
+import head from './head';
+import prop from './prop';
+import isNil from './isNil';
+import isArray from './isArray';
+import isNumber from './isNumber';
+import has from './has';
+import assoc from './assoc';
+
+const assocPath = (path, value, obj) => {
+  if (length(path) < 1) return value;
+
+  const idx = head(path);
+  const nextPath = slice(1, Infinity, path);
+  let val = value;
+
+  if (length(path) > 0) {
+    const nextObj =
+      !isNil(obj) && has(idx, obj) // eslint-disable-line no-nested-ternary
+        ? prop(idx, obj)
+        : isNumber(path[1]) ? [] : {};
+
+    val = assocPath(nextPath, val, nextObj);
+  }
+
+  if (isNumber(idx) && isArray(obj)) {
+    const arr = [...obj];
+    arr[idx] = val;
+    return arr;
+  }
+
+  return assoc(idx, val, obj);
+};
+
+export default assocPath;

src/index.js

@@ -2,6 +2,7 @@ import allPass from './allPass';
 import anyPass from './anyPass';
 import append from './append';
 import assoc from './assoc';
+import assocPath from './assocPath';
 import compose from './compose';
 import concat from './concat';
 import curry from './curry';
@@ -34,6 +35,7 @@ export {
   anyPass,
   append,
   assoc,
+  assocPath,
   compose,
   concat,
   curry,