# Node.js Example for Calling API

#### Prerequisites

* [You need a valid **API Key** and **API Secret**](/en/getting-started/buy-energy-via-api-on-catfee/api-overview.md#apply-api-info).
* Ensure that your Node.js environment has the `axios` library installed. You can install it using:

```bash
npm install axios
```

***

#### Example Code

```js
const axios = require('axios');
const crypto = require('crypto');

const API_KEY = 'your_api_key'; // Replace with your actual API Key
const API_SECRET = 'your_api_secret'; // Replace with your actual API Secret
const BASE_URL = 'https://api.catfee.io';

// Generate the current timestamp in ISO 8601 format
function generateTimestamp() {
    return new Date().toISOString();
}

// Build request path including query parameters
function buildRequestPath(path, queryParams) {
    if (!queryParams || Object.keys(queryParams).length === 0) {
        return path;
    }
    const queryString = new URLSearchParams(queryParams).toString();
    return `${path}?${queryString}`;
}

// Generate signature using HMAC-SHA256
function generateSignature(timestamp, method, requestPath) {
    const signString = timestamp + method + requestPath;
    return crypto.createHmac('sha256', API_SECRET)
                 .update(signString)
                 .digest('base64');
}

// Create and send HTTP request
async function createRequest(url, method, timestamp, signature) {
    const headers = {
        'Content-Type': 'application/json',
        'CF-ACCESS-KEY': API_KEY,
        'CF-ACCESS-SIGN': signature,
        'CF-ACCESS-TIMESTAMP': timestamp
    };

    try {
        const response = await axios({
            url,
            method,
            headers,
        });
        return response.data;
    } catch (error) {
        console.error('Error: ', error.response ? error.response.data : error.message);
        throw error;
    }
}

async function main() {
    const method = 'POST'; // Can be changed to "GET", "PUT", "DELETE"
    const path = '/v1/order';

    // Example: Create an order
    const queryParams = {
        quantity: '65000',
        receiver: 'TRON_ADDRESS',
        duration: '1h'
    };

    // Generate timestamp, request path, and signature
    const timestamp = generateTimestamp();
    const requestPath = buildRequestPath(path, queryParams);
    const signature = generateSignature(timestamp, method, requestPath);

    // Compose full request URL
    const url = BASE_URL + requestPath;

    // Send request
    try {
        const response = await createRequest(url, method, timestamp, signature);
        console.log('Response Data: ', response);
    } catch (error) {
        console.error('Request failed', error);
    }
}

// Run the main function
main();
```

***

#### Code Explanation

* **generateTimestamp()**\
  Returns the current UTC timestamp in ISO 8601 format using JavaScript's `toISOString()` method.
* **buildRequestPath()**\
  Constructs the full URL path by appending URL-encoded query parameters. `URLSearchParams` is used to format the query string.
* **generateSignature()**\
  Signs the string composed of `timestamp + method + requestPath` using the HMAC-SHA256 algorithm with your `API_SECRET`, then encodes the result in Base64.
* **createRequest()**\
  Sends the HTTP request using the `axios` library. Sets headers including `CF-ACCESS-KEY`, `CF-ACCESS-SIGN`, and `CF-ACCESS-TIMESTAMP`.
* **main()**\
  Defines the HTTP method and request path, prepares query parameters, generates the necessary headers, and sends the request.

***

#### Notes

* **API Key and Secret**\
  Make sure to replace `API_KEY` and `API_SECRET` with the actual values you obtained from CatFee.IO.
* **Query Parameter Order**\
  This example uses `URLSearchParams` to build the query string without sorting the parameters.
* **Error Handling**\
  Uses `try-catch` to catch and log any potential errors. Server errors can be accessed via `error.response`.
* **Request Method**\
  The example supports `POST`, `GET`, `PUT`, and `DELETE`. You can change the `method` variable accordingly.
* **Response Handling**\
  If the request is successful, `axios` returns `response.data`, which is the response body. You can parse it based on your needs (e.g., JSON).

***

#### Summary

This example demonstrates how to securely call the CatFee.IO REST API in a Node.js environment. It includes HMAC-SHA256 signature generation for request verification and supports multiple HTTP methods. You can modify and expand the code based on your specific API use cases.


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