Express.js is a web application framework for Node.js that allows you to create a query. To do this, you need to set up a route and a function to handle the query.

For example, this code block will create a query route that will return the value ofqueryParam when aGET request is sent to/query:

// Setup the query routeapp.get('/query', (req, res) => {  // Get the query parameter  const queryParam = req.query.param;  // Send the response  res.send(queryParam);});

When aGET request is sent to/query?param=hello, the response will behello.

The code block above consists of the following parts:

1. app.get('/query', (req, res) => { - This sets up the query route. It specifies that when aGET request is sent to/query, the following function will be called.
2. const queryParam = req.query.param; - This gets the query parameter (param) from the request.
3. res.send(queryParam); - This sends the response. In this case, it's the value ofqueryParam.

For more information on Express.js, see thedocumentation.

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