Merge branch 'main' of github.com:chenbimo/yidash

lib/array/countByProperty.js

@@ -0,0 +1,38 @@
+/**
+ * @alias yd_array_countByProperty
+ * @category array
+ * @param {Array} items - 对象数组。
+ * @param {string} property - 要统计的属性名。
+ * @returns {object} - 一个包含每个属性值出现次数的对象。如果输入无效，则返回空对象。
+ * @author penn <https://github.com/penn201500>
+ * @example
+ * const characters = [
+ *    { name: 'Luke Skywalker', eye_color: 'blue' },
+ *    { name: 'Darth Vader', eye_color: 'yellow' },
+ *    { name: 'Anakin Skywalker' } // 没有 eye_color 属性
+ * ];
+ * console.log(countByProperty(characters, 'eye_color'));
+ * // 输出: { blue: 1, yellow: 1 }
+ * @description 统计数组中对象指定属性的出现次数。
+ */
+export default (items, property) => {
+    // 检查 items 类型是否为数组
+    if (!Array.isArray(items)) {
+        console.error('countByProperty: items 必须是一个数组');
+        return {};
+    }
+
+    // 检查 property 是否为有效的字符串
+    if (typeof property !== 'string' || property.trim() === '') {
+        console.error('countByProperty: property 必须是一个非空字符串');
+        return {};
+    }
+
+    return items.reduce((acc, item) => {
+        // 检查对象是否有指定的属性，并且属性值不是 undefined
+        if (item.hasOwnProperty(property) && item[property] !== undefined && item[property] !== null) {
+            acc[item[property]] = (acc[item[property]] || 0) + 1;
+        }
+        return acc;
+    }, {});
+};

lib/array/countByProperty.test.js

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+import { it, expect, describe } from 'vitest';
+import yd_array_countByProperty from './countByProperty';
+
+const characters = [{ name: 'Luke Skywalker', eye_color: 'blue' }, { name: 'Darth Vader', eye_color: 'yellow' }, { name: 'Anakin Skywalker' }];
+
+describe('yd_array_countByProperty', () => {
+    it('should return correct count of a property', () => {
+        const result = yd_array_countByProperty(characters, 'eye_color');
+        expect(result).toEqual({ blue: 1, yellow: 1 });
+    });
+
+    it('should return an empty object if the array is empty', () => {
+        const result = yd_array_countByProperty([], 'eye_color');
+        expect(result).toEqual({});
+    });
+
+    it('should return an empty object if property is not a valid string', () => {
+        const result = yd_array_countByProperty(characters, 123);
+        expect(result).toEqual({});
+    });
+
+    it('should return an empty object if items is not an array', () => {
+        const result = yd_array_countByProperty('characters', 'eye_color');
+        expect(result).toEqual({});
+    });
+
+    it('should return an empty object if all objects does not have the specified property', () => {
+        const result = yd_array_countByProperty([{ name: 'Luke Skywalker' }, { name: 'Darth Vader' }], 'eye_color');
+        expect(result).toEqual({});
+    });
+
+    it('should skip objects where the specified property is undefined', () => {
+        const modifiedCharacters = [
+            { name: 'Luke Skywalker', eye_color: 'blue' },
+            { name: 'Darth Vader', eye_color: 'yellow' },
+            { name: 'Anakin Skywalker', eye_color: undefined }
+        ];
+        const result = yd_array_countByProperty(modifiedCharacters, 'eye_color');
+        expect(result).toEqual({ blue: 1, yellow: 1 });
+    });
+});