feat: add deep-merge util

packages/opentelemetry-core/src/utils/deep-merge.ts

@@ -0,0 +1,45 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+function deepMerge(
+  target: { [prop: string]: any },
+  source: { [prop: string]: any }
+) {
+  const merged = target;
+  for (const prop in source) {
+    if (propIsArrayInBoth(source, prop, target)) {
+      merged[prop] = source[prop].concat(target[prop]);
+    } else if (propIsObj(source, prop)) {
+      merged[prop] = deepMerge(target[prop], source[prop]);
+    } else {
+      merged[prop] = source[prop];
+    }
+  }
+  return merged;
+}
+
+function propIsObj(source: { [prop: string]: any }, prop: string) {
+  return Object.prototype.toString.call(source[prop]) === '[object Object]';
+}
+
+function propIsArrayInBoth(
+  source: { [prop: string]: any },
+  prop: string,
+  target: { [prop: string]: any }
+) {
+  return Array.isArray(source[prop]) && Array.isArray(target[prop]);
+}
+
+export default deepMerge;

packages/opentelemetry-core/test/utils/deep-merge.test.ts

@@ -0,0 +1,34 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+import * as assert from 'assert';
+import deepMerge from '../../src/utils/deep-merge';
+
+describe('deepMerge', () => {
+  it('should deep merge two objects', () => {
+    const target = { a: 1, b: 1, d: 1, e: [4, 5, 6], f: { g: 1, h: 2 } };
+    const source = { a: 1, b: 2, c: 2, e: [1, 2, 3], f: { h: 1, i: 1 } };
+    const expected = {
+      a: 1,
+      b: 2,
+      c: 2,
+      d: 1,
+      e: [1, 2, 3, 4, 5, 6],
+      f: { g: 1, h: 1, i: 1 },
+    };
+    const merged = deepMerge(target, source);
+    assert.deepEqual(merged, expected);
+  });
+});