Add count tokens example

Author: gericdong

genai/count-tokens/counttoken-with-txt.js

@@ -0,0 +1,46 @@
+// Copyright 2025 Google LLC
+//
+// 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.
+
+'use strict';
+
+// [START googlegenaisdk_counttoken_with_txt]
+const {GoogleGenAI} = require('@google/genai');
+
+const GOOGLE_CLOUD_PROJECT = process.env.GOOGLE_CLOUD_PROJECT;
+const GOOGLE_CLOUD_LOCATION = process.env.GOOGLE_CLOUD_LOCATION || 'global';
+
+async function countTokens(
+  projectId = GOOGLE_CLOUD_PROJECT,
+  location = GOOGLE_CLOUD_LOCATION
+) {
+  const ai = new GoogleGenAI({
+    vertexai: true,
+    project: projectId,
+    location: location,
+  });
+
+  const response = await ai.models.countTokens({
+    model: 'gemini-2.0-flash',
+    contents: 'What is the highest mountain in Africa?',
+  });
+
+  console.log(response);
+
+  return response.totalTokens;
+}
+// [END googlegenaisdk_counttoken_with_txt]
+
+module.exports = {
+  countTokens,
+};

genai/test/counttoken-with-txt.test.js

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+// Copyright 2025 Google LLC
+//
+// 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.
+
+'use strict';
+
+const {assert} = require('chai');
+const {describe, it} = require('mocha');
+
+const projectId = process.env.CAIP_PROJECT_ID;
+const sample = require('../count-tokens/counttoken-with-txt.js');
+
+describe('counttoken-with-txt', async () => {
+  it('should return the total token count for a text prompt', async () => {
+    const output = await sample.countTokens(projectId);
+    assert(output > 0);
+  });
+});