mapValues method, docs, tests

README.md

@@ -141,6 +141,7 @@ A ES module bundle is included under `dist/absurdum.esm.js` and is defined as th
 - [invert][objects.invert]
 - [keys][objects.keys]
 - [mapKeys][objects.mapKeys]
+- [mapValues][objects.mapValues]
 - [merge][objects.merge]
 - [pick][objects.pick]
 - [values][objects.values]
@@ -155,6 +156,7 @@ A ES module bundle is included under `dist/absurdum.esm.js` and is defined as th
 [objects.invert]: ./docs/objects/invert.md
 [objects.keys]: ./docs/objects/keys.md
 [objects.mapKeys]: ./docs/objects/mapKeys.md
+[objects.mapValues]: ./docs/objects/mapValues.md
 [objects.merge]: ./docs/objects/merge.md
 [objects.pick]: ./docs/objects/pick.md
 [objects.values]: ./docs/objects/values.md

src/objects/index.d.ts

@@ -8,6 +8,7 @@ export { include } from "./include.js";
 export { invert } from "./invert.js";
 export { keys } from "./keys.js";
 export { mapKeys } from "./mapKeys.js";
+export { mapValues } from "./mapValues.js";
 export { merge } from "./merge.js";
 export { pick } from "./pick.js";
 export { values } from "./values.js";

src/objects/index.js

@@ -8,6 +8,7 @@ export { include } from './include.js';
 export { invert } from './invert.js';
 export { keys } from './keys.js';
 export { mapKeys } from './mapKeys.js';
+export { mapValues } from './mapValues.js';
 export { merge } from './merge.js';
 export { pick } from './pick.js';
 export { values } from './values.js';

src/objects/mapValues.js

@@ -0,0 +1,21 @@
+/**
+ * MapKeys iterates over an object and applies a function to each value
+ *
+ * @param {Object} object input object
+ * @param {Function} func map function
+ * @returns {Object} object with mutated values
+ *
+ * @example
+ * const result = objects.mapValues({ a: 1, b: 2, c: 3 }, value => `neat_${value}`);
+ * console.log(result);
+ * > { a: neat_1, b: neat_2, c: neat_3 }
+ */
+function mapValues (object, func) {
+  if (typeof func !== 'function') { return object; }
+  return Object.entries(object).reduce((acc, [key, value]) => ({
+    ...acc,
+    [key]: func(value, key, object)
+  }), {});
+}
+
+export { mapValues };

src/objects/mapValues.spec.js

@@ -0,0 +1,44 @@
+import test from 'tape';
+import { objects } from '../../index.js';
+
+test('objects.mapValues(object, func) - returns an object with updated values', t => {
+  const expect = { a: 'neat_1', b: 'neat_2', c: 'neat_3' };
+  const result = objects.mapValues({ a: 1, b: 2, c: 3 }, value => `neat_${value}`);
+
+  t.equal(Object.prototype.toString.call(result), '[object Object]', 'return type');
+  t.deepEqual(result, expect, 'output value');
+
+  t.end();
+});
+
+test('objects.mapValues(object, func) - returns an object with updated keys using keys, values, and the object as arguments', t => {
+  const expect = { a: 'a_1_1', b: 'b_2_1', c: 'c_3_1' };
+  const result = objects.mapValues({ a: 1, b: 2, c: 3 }, function (value, key, object) {
+    return `${key}_${value}_${object.a}`;
+  });
+
+  t.equal(Object.prototype.toString.call(result), '[object Object]', 'return type');
+  t.deepEqual(result, expect, 'output value');
+
+  t.end();
+});
+
+test('objects.mapValues(object) - returns the input object if no function is applied', t => {
+  const expect = { a: 1, b: 2, c: 3 };
+  const result = objects.mapValues({ a: 1, b: 2, c: 3 });
+
+  t.equal(Object.prototype.toString.call(result), '[object Object]', 'return type');
+  t.deepEqual(result, expect, 'output value');
+
+  t.end();
+});
+
+test('objects.mapValues(object, func) - should not mutate the input', t => {
+  const input = { a: 1, b: 2, c: 3 };
+  const expect = { a: 1, b: 2, c: 3 };
+  objects.get(input, value => value + 3);
+
+  t.deepEqual(input, expect, 'input mutation');
+
+  t.end();
+});