expressjsHow can I use query parameters in an Express.js application?

Query parameters are used to filter and sort data in an Express.js application. To use query parameters, first define a route in the Express.js application that will accept the query parameters. For example:

app.get('/users', (req, res) => {
  // code to handle query parameters
});

The req object contains the query parameters in the query property. For example, if the route is called with /users?name=John&age=20, then req.query will contain the object {name: "John", age: 20}.

The code to handle the query parameters can then use the req.query object to filter and sort the data. For example, to find all users with the name John and age 20:

const users = [
  {name: "John", age: 20},
  {name: "Bob", age: 25},
  {name: "John", age: 30},
];

const filteredUsers = users.filter(user =>
  user.name === req.query.name && user.age === req.query.age
);

// filteredUsers = [{name: "John", age: 20}]

Code explanation

1. app.get('/users', (req, res) => { ... }): Defines a route that accepts query parameters.
2. req.query: Contains the query parameters.
3. users.filter(user => ...): Filters the users array based on the query parameters.

Helpful links

• Express.js routing documentation
• MDN Web API: URLSearchParams

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