Transformers Js

Transformers.js enables running state-of-the-art machine learning models directly in JavaScript, both in browsers and Node.js environments, with no server required.

When to Use This Skill

Use this skill when you need to:

• -Run ML models for text analysis, generation, or translation in JavaScript
• -Perform image classification, object detection, or segmentation
• -Implement speech recognition or audio processing
• -Build multimodal AI applications (text-to-image, image-to-text, etc.)
• -Run models client-side in the browser without a backend

Installation

NPM Installation

npm install @huggingface/transformers

Browser Usage (CDN)

<script type="module">
  import { pipeline } from 'https://cdn.jsdelivr.net/npm/@huggingface/transformers';
</script>

Core Concepts

1. Pipeline API

The pipeline API is the easiest way to use models. It groups together preprocessing, model inference, and postprocessing:

import { pipeline } from '@huggingface/transformers';

// Create a pipeline for a specific task
const pipe = await pipeline('sentiment-analysis');

// Use the pipeline
const result = await pipe('I love transformers!');
// Output: [{ label: 'POSITIVE', score: 0.999817686 }]

// IMPORTANT: Always dispose when done to free memory
await classifier.dispose();

⚠️ Memory Management: All pipelines must be disposed with pipe.dispose() when finished to prevent memory leaks. See examples in Code Examples for cleanup patterns across different environments.

2. Model Selection

You can specify a custom model as the second argument:

const pipe = await pipeline(
  'sentiment-analysis',
  'Xenova/bert-base-multilingual-uncased-sentiment'
);

Finding Models:

Browse available Transformers.js models on Hugging Face Hub:

• -All models: https://huggingface.co/models?library=transformers.js&sort=trending
• -By task: Add pipeline_tag parameter
• -Text generation: https://huggingface.co/models?pipeline_tag=text-generation&library=transformers.js&sort=trending
• -Image classification: https://huggingface.co/models?pipeline_tag=image-classification&library=transformers.js&sort=trending
• -Speech recognition: https://huggingface.co/models?pipeline_tag=automatic-speech-recognition&library=transformers.js&sort=trending

Tip: Filter by task type, sort by trending/downloads, and check model cards for performance metrics and usage examples.

3. Device Selection

Choose where to run the model:

// Run on CPU (default for WASM)
const pipe = await pipeline('sentiment-analysis', 'model-id');

// Run on GPU (WebGPU - experimental)
const pipe = await pipeline('sentiment-analysis', 'model-id', {
  device: 'webgpu',
});

4. Quantization Options

Control model precision vs. performance:

// Use quantized model (faster, smaller)
const pipe = await pipeline('sentiment-analysis', 'model-id', {
  dtype: 'q4',  // Options: 'fp32', 'fp16', 'q8', 'q4'
});

Supported Tasks

Note: All examples below show basic usage.

Natural Language Processing

#### Text Classification

const classifier = await pipeline('text-classification');
const result = await classifier('This movie was amazing!');

#### Named Entity Recognition (NER)

const ner = await pipeline('token-classification');
const entities = await ner('My name is John and I live in New York.');

#### Question Answering

const qa = await pipeline('question-answering');
const answer = await qa({
  question: 'What is the capital of France?',
  context: 'Paris is the capital and largest city of France.'
});

#### Text Generation

const generator = await pipeline('text-generation', 'onnx-community/gemma-3-270m-it-ONNX');
const text = await generator('Once upon a time', {
  max_new_tokens: 100,
  temperature: 0.7
});

For streaming and chat: See [Text Generation Guide](./references/TEXT_GENERATION.md) for:

• -Streaming token-by-token output with TextStreamer
• -Chat/conversation format with system/user/assistant roles
• -Generation parameters (temperature, top_k, top_p)
• -Browser and Node.js examples
• -React components and API endpoints

#### Translation

const translator = await pipeline('translation', 'Xenova/nllb-200-distilled-600M');
const output = await translator('Hello, how are you?', {
  src_lang: 'eng_Latn',
  tgt_lang: 'fra_Latn'
});

#### Summarization

const summarizer = await pipeline('summarization');
const summary = await summarizer(longText, {
  max_length: 100,
  min_length: 30
});

#### Zero-Shot Classification

const classifier = await pipeline('zero-shot-classification');
const result = await classifier('This is a story about sports.', ['politics', 'sports', 'technology']);

Computer Vision

#### Image Classification

const classifier = await pipeline('image-classification');
const result = await classifier('https://example.com/image.jpg');
// Or with local file
const result = await classifier(imageUrl);

#### Object Detection

const detector = await pipeline('object-detection');
const objects = await detector('https://example.com/image.jpg');
// Returns: [{ label: 'person', score: 0.95, box: { xmin, ymin, xmax, ymax } }, ...]

#### Image Segmentation

const segmenter = await pipeline('image-segmentation');
const segments = await segmenter('https://example.com/image.jpg');

#### Depth Estimation

const depthEstimator = await pipeline('depth-estimation');
const depth = await depthEstimator('https://example.com/image.jpg');

#### Zero-Shot Image Classification

const classifier = await pipeline('zero-shot-image-classification');
const result = await classifier('image.jpg', ['cat', 'dog', 'bird']);

Audio Processing

#### Automatic Speech Recognition

const transcriber = await pipeline('automatic-speech-recognition');
const result = await transcriber('audio.wav');
// Returns: { text: 'transcribed text here' }

#### Audio Classification

const classifier = await pipeline('audio-classification');
const result = await classifier('audio.wav');

#### Text-to-Speech

const synthesizer = await pipeline('text-to-speech', 'Xenova/speecht5_tts');
const audio = await synthesizer('Hello, this is a test.', {
  speaker_embeddings: speakerEmbeddings
});

Multimodal

#### Image-to-Text (Image Captioning)

const captioner = await pipeline('image-to-text');
const caption = await captioner('image.jpg');

#### Document Question Answering

const docQA = await pipeline('document-question-answering');
const answer = await docQA('document-image.jpg', 'What is the total amount?');

#### Zero-Shot Object Detection

const detector = await pipeline('zero-shot-object-detection');
const objects = await detector('image.jpg', ['person', 'car', 'tree']);

Feature Extraction (Embeddings)

const extractor = await pipeline('feature-extraction');
const embeddings = await extractor('This is a sentence to embed.');
// Returns: tensor of shape [1, sequence_length, hidden_size]

// For sentence embeddings (mean pooling)
const extractor = await pipeline('feature-extraction', 'onnx-community/all-MiniLM-L6-v2-ONNX');
const embeddings = await extractor('Text to embed', { pooling: 'mean', normalize: true });

Finding and Choosing Models

Browsing the Hugging Face Hub

Discover compatible Transformers.js models on Hugging Face Hub:

Base URL (all models):

https://huggingface.co/models?library=transformers.js&sort=trending

Filter by task using the pipeline_tag parameter:

Sort options:

• -&sort=trending - Most popular recently
• -&sort=downloads - Most downloaded overall
• -&sort=likes - Most liked by community
• -&sort=modified - Recently updated

Choosing the Right Model

Consider these factors when selecting a model:

1. Model Size

• -Small (< 100MB): Fast, suitable for browsers, limited accuracy
• -Medium (100MB - 500MB): Balanced performance, good for most use cases
• -Large (> 500MB): High accuracy, slower, better for Node.js or powerful devices

2. Quantization

Models are often available in different quantization levels:

• -fp32 - Full precision (largest, most accurate)
• -fp16 - Half precision (smaller, still accurate)
• -q8 - 8-bit quantized (much smaller, slight accuracy loss)
• -q4 - 4-bit quantized (smallest, noticeable accuracy loss)

3. Task Compatibility

Check the model card for:

• -Supported tasks (some models support multiple tasks)
• -Input/output formats
• -Language support (multilingual vs. English-only)
• -License restrictions

4. Performance Metrics

Model cards typically show:

• -Accuracy scores
• -Benchmark results
• -Inference speed
• -Memory requirements

Example: Finding a Text Generation Model

// 1. Visit: https://huggingface.co/models?pipeline_tag=text-generation&library=transformers.js&sort=trending

// 2. Browse and select a model (e.g., onnx-community/gemma-3-270m-it-ONNX)

// 3. Check model card for:
//    - Model size: ~270M parameters
//    - Quantization: q4 available
//    - Language: English
//    - Use case: Instruction-following chat

// 4. Use the model:
import { pipeline } from '@huggingface/transformers';

const generator = await pipeline(
  'text-generation',
  'onnx-community/gemma-3-270m-it-ONNX',
  { dtype: 'q4' } // Use quantized version for faster inference
);

const output = await generator('Explain quantum computing in simple terms.', {
  max_new_tokens: 100
});

await generator.dispose();

Tips for Model Selection

1. Start Small: Test with a smaller model first, then upgrade if needed

2. Check ONNX Support: Ensure the model has ONNX files (look for onnx folder in model repo)

3. Read Model Cards: Model cards contain usage examples, limitations, and benchmarks

4. Test Locally: Benchmark inference speed and memory usage in your environment

5. Community Models: Look for models by Xenova (Transformers.js maintainer) or onnx-community

6. Version Pin: Use specific git commits in production for stability:

   const pipe = await pipeline('task', 'model-id', { revision: 'abc123' });

Advanced Configuration

Environment Configuration (env)

The env object provides comprehensive control over Transformers.js execution, caching, and model loading.

Quick Overview:

import { env } from '@huggingface/transformers';

// View version
console.log(env.version); // e.g., '3.8.1'

// Common settings
env.allowRemoteModels = true;  // Load from Hugging Face Hub
env.allowLocalModels = false;  // Load from file system
env.localModelPath = '/models/'; // Local model directory
env.useFSCache = true;         // Cache models on disk (Node.js)
env.useBrowserCache = true;    // Cache models in browser
env.cacheDir = './.cache';     // Cache directory location

Configuration Patterns:

// Development: Fast iteration with remote models
env.allowRemoteModels = true;
env.useFSCache = true;

// Production: Local models only
env.allowRemoteModels = false;
env.allowLocalModels = true;
env.localModelPath = '/app/models/';

// Custom CDN
env.remoteHost = 'https://cdn.example.com/models';

// Disable caching (testing)
env.useFSCache = false;
env.useBrowserCache = false;

For complete documentation on all configuration options, caching strategies, cache management, pre-downloading models, and more, see:

→ [Configuration Reference](./references/CONFIGURATION.md)

Working with Tensors

import { AutoTokenizer, AutoModel } from '@huggingface/transformers';

// Load tokenizer and model separately for more control
const tokenizer = await AutoTokenizer.from_pretrained('bert-base-uncased');
const model = await AutoModel.from_pretrained('bert-base-uncased');

// Tokenize input
const inputs = await tokenizer('Hello world!');

// Run model
const outputs = await model(inputs);

Batch Processing

const classifier = await pipeline('sentiment-analysis');

// Process multiple texts
const results = await classifier([
  'I love this!',
  'This is terrible.',
  'It was okay.'
]);

Browser-Specific Considerations

WebGPU Usage

WebGPU provides GPU acceleration in browsers:

const pipe = await pipeline('text-generation', 'onnx-community/gemma-3-270m-it-ONNX', {
  device: 'webgpu',
  dtype: 'fp32'
});

Note: WebGPU is experimental. Check browser compatibility and file issues if problems occur.

WASM Performance

Default browser execution uses WASM:

// Optimized for browsers with quantization
const pipe = await pipeline('sentiment-analysis', 'model-id', {
  dtype: 'q8'  // or 'q4' for even smaller size
});

Progress Tracking & Loading Indicators

Models can be large (ranging from a few MB to several GB) and consist of multiple files. Track download progress by passing a callback to the pipeline() function:

import { pipeline } from '@huggingface/transformers';

// Track progress for each file
const fileProgress = {};

function onProgress(info) {
  console.log(`${info.status}: ${info.file}`);
  
  if (info.status === 'progress') {
    fileProgress[info.file] = info.progress;
    console.log(`${info.file}: ${info.progress.toFixed(1)}%`);
  }
  
  if (info.status === 'done') {
    console.log(`✓ ${info.file} complete`);
  }
}

// Pass callback to pipeline
const classifier = await pipeline('sentiment-analysis', null, {
  progress_callback: onProgress
});

Progress Info Properties:

interface ProgressInfo {
  status: 'initiate' | 'download' | 'progress' | 'done' | 'ready';
  name: string;      // Model id or path
  file: string;      // File being processed
  progress?: number; // Percentage (0-100, only for 'progress' status)
  loaded?: number;   // Bytes downloaded (only for 'progress' status)
  total?: number;    // Total bytes (only for 'progress' status)
}

For complete examples including browser UIs, React components, CLI progress bars, and retry logic, see:

→ [Pipeline Options - Progress Callback](./references/PIPELINE_OPTIONS.md#progress-callback)

Error Handling

try {
  const pipe = await pipeline('sentiment-analysis', 'model-id');
  const result = await pipe('text to analyze');
} catch (error) {
  if (error.message.includes('fetch')) {
    console.error('Model download failed. Check internet connection.');
  } else if (error.message.includes('ONNX')) {
    console.error('Model execution failed. Check model compatibility.');
  } else {
    console.error('Unknown error:', error);
  }
}

Performance Tips

1. Reuse Pipelines: Create pipeline once, reuse for multiple inferences

2. Use Quantization: Start with q8 or q4 for faster inference

3. Batch Processing: Process multiple inputs together when possible

4. Cache Models: Models are cached automatically (see [Caching Reference](./references/CACHE.md) for details on browser Cache API, Node.js filesystem cache, and custom implementations)

5. WebGPU for Large Models: Use WebGPU for models that benefit from GPU acceleration

6. Prune Context: For text generation, limit max_new_tokens to avoid memory issues

7. Clean Up Resources: Call pipe.dispose() when done to free memory

Memory Management

IMPORTANT: Always call pipe.dispose() when finished to prevent memory leaks.

const pipe = await pipeline('sentiment-analysis');
const result = await pipe('Great product!');
await pipe.dispose();  // ✓ Free memory (100MB - several GB per model)

When to dispose:

• -Application shutdown or component unmount
• -Before loading a different model
• -After batch processing in long-running apps

Models consume significant memory and hold GPU/CPU resources. Disposal is critical for browser memory limits and server stability.

For detailed patterns (React cleanup, servers, browser), see [Code Examples](./references/EXAMPLES.md)

Troubleshooting

Model Not Found

• -Verify model exists on Hugging Face Hub
• -Check model name spelling
• -Ensure model has ONNX files (look for onnx folder in model repo)

Memory Issues

• -Use smaller models or quantized versions (dtype: 'q4')
• -Reduce batch size
• -Limit sequence length with max_length

WebGPU Errors

• -Check browser compatibility (Chrome 113+, Edge 113+)
• -Try dtype: 'fp16' if fp32 fails
• -Fall back to WASM if WebGPU unavailable

Reference Documentation

This Skill

• -[Pipeline Options](./references/PIPELINE_OPTIONS.md) - Configure pipeline() with progress_callback, device, dtype, etc.
• -[Configuration Reference](./references/CONFIGURATION.md) - Global env configuration for caching and model loading
• -[Caching Reference](./references/CACHE.md) - Browser Cache API, Node.js filesystem cache, and custom cache implementations
• -[Text Generation Guide](./references/TEXT_GENERATION.md) - Streaming, chat format, and generation parameters
• -[Model Architectures](./references/MODEL_ARCHITECTURES.md) - Supported models and selection tips
• -[Code Examples](./references/EXAMPLES.md) - Real-world implementations for different runtimes

Official Transformers.js

• -Official docs: https://huggingface.co/docs/transformers.js
• -API reference: https://huggingface.co/docs/transformers.js/api/pipelines
• -Model hub: https://huggingface.co/models?library=transformers.js
• -GitHub: https://github.com/huggingface/transformers.js
• -Examples: https://github.com/huggingface/transformers.js/tree/main/examples

Best Practices

1. Always Dispose Pipelines: Call pipe.dispose() when done - critical for preventing memory leaks

2. Start with Pipelines: Use the pipeline API unless you need fine-grained control

3. Test Locally First: Test models with small inputs before deploying

4. Monitor Model Sizes: Be aware of model download sizes for web applications

5. Handle Loading States: Show progress indicators for better UX

6. Version Pin: Pin specific model versions for production stability

7. Error Boundaries: Always wrap pipeline calls in try-catch blocks

8. Progressive Enhancement: Provide fallbacks for unsupported browsers

9. Reuse Models: Load once, use many times - don't recreate pipelines unnecessarily

10. Graceful Shutdown: Dispose models on SIGTERM/SIGINT in servers

Quick Reference: Task IDs

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This skill enables you to integrate state-of-the-art machine learning capabilities directly into JavaScript applications without requiring separate ML servers or Python environments.