Easier way to update data with node-postgres?

You could always roll out a function like so:

function updateProductByID (id, cols) {
  // Setup static beginning of query
  var query = ['UPDATE products'];
  query.push('SET');

  // Create another array storing each set command
  // and assigning a number value for parameterized query
  var set = [];
  Object.keys(cols).forEach(function (key, i) {
    set.push(key + ' = ($' + (i + 1) + ')'); 
  });
  query.push(set.join(', '));

  // Add the WHERE statement to look up by id
  query.push('WHERE pr_id = ' + id );

  // Return a complete query string
  return query.join(' ');
}

And then use it as such:

/*
 Post /api/project/products/:pr_id HTTP/1.1
 */
exports.updateProduct = function(req, res){
  pg.connect(cs, function(err, client, done) {

    // Setup the query
    var query = updateProductByID(req.params.pr_id, req.body);

    // Turn req.body into an array of values
    var colValues = Object.keys(req.body).map(function (key) {
      return req.body[key];
    });

    client.query(query, colValues, function(err, result) {
      if (handleErr(err, done)) return;
      done();
      sendResponse(res, result.rows[0]);
    });
  });
};

Or, if an ORM is something you need because you'll be doing a lot like the above, you should check out modules like Knex.js

Good answers have already been given, but IMHO not good enough in one aspect, they all lacks good abstraction. I will try to provide more abstracted way of updating your data in postgres using node-postgres.

It is always good practice to follow official documentation, following code structure was taken from node-postgres, you can extend it however you like:

here is mine, this is where you interact with your database

const { Pool } = require("pg");
const connection = require("./connection.json");
const pool = new Pool(connection);
const { insert, select, remove, update } = require("./helpers");


/**
 * The main mechanism to avoid SQL Injection is by escaping the input parameters.
 * Any good SQL library should have a way to achieve this.
 * PG library allows you to do this by placeholders `($1, $2)`
 */
module.exports = {
  query: (text, params, callback) => {
    const start = Date.now();

    return pool.query(text, params, (err, res) => {
      const duration = Date.now() - start;
      console.log("executed query", { text, duration, rows: res.rowCount });
      callback(err, res);
    });
  },

  getClient: callback => {
    pool.connect((err, client, done) => {
      const query = client.query;
      // monkey patch the query method to keep track of the last query executed
      client.query = (...args) => {
        client.lastQuery = args;
        return query.apply(client, args);
      };
      // set a timeout of 5 seconds, after which we will log this client's last query
      const timeout = setTimeout(() => {
        console.error("A client has been checked out for more than 5 seconds!");
        console.error(
          `The last executed query on this client was: ${client.lastQuery}`
        );
      }, 5000);
      const release = err => {
        // call the actual 'done' method, returning this client to the pool
        done(err);
        // clear our timeout
        clearTimeout(timeout);
        // set the query method back to its old un-monkey-patched version
        client.query = query;
      };
      callback(err, client, release);
    });
  },

  /**
   * Updates data
   *
   * entity: table name, e.g, users 
   * conditions: { id: "some-unique-user-id", ... }
   * fields: list of desired columns to update { username: "Joe", ... }
   */
  updateOne: async (entity, conditions, fields) => {
    if (!entity) throw new Error("no entity table specified");
    if (Utils.isObjEmpty(conditions))
      throw new Error("no conditions specified");

    let resp;   
    const { text, values } = update(entity, conditions, fields);

    try {
      rs = await pool.query(text, values);
      resp = rs.rows[0];
    } catch (err) {
      console.error(err);
      throw err;
    }

    return resp;
  },

  createOne: async (entity, data) => {
  },

  deleteOne: async (entity, conditions, data) => {
  },

  findAll: async (entity, conditions, fields) => {
  },

  // ... other methods
};

here is helper methods for CRUD operations, they will prepare query text with prepared values:

/**
 * tableName: `users`
 * conditions: { id: 'joe-unique-id', ... }
 * data: { username: 'Joe', age: 28, status: 'active', ... }
 *
 *  "UPDATE users SET field_1 = $1, field_2 = $2, field_3 = $3, ... ( WHERE ...) RETURNING *";
 */
exports.update = (tableName, conditions = {}, data = {}) => {
  const dKeys = Object.keys(data);
  const dataTuples = dKeys.map((k, index) => `${k} = $${index + 1}`);
  const updates = dataTuples.join(", ");
  const len = Object.keys(data).length;

  let text = `UPDATE ${tableName} SET ${updates} `;

  if (!Utils.isObjEmpty(conditions)) {
    const keys = Object.keys(conditions);
    const condTuples = keys.map((k, index) => `${k} = $${index + 1 + len} `);
    const condPlaceholders = condTuples.join(" AND ");

    text += ` WHERE ${condPlaceholders} RETURNING *`;
  }

  const values = [];
  Object.keys(data).forEach(key => {
    values.push(data[key]);
  });
  Object.keys(conditions).forEach(key => {
    values.push(conditions[key]);
  });

  return { text, values };
};

exports.select = (tableName, conditions = {}, data = ["*"]) => {...}
exports.insert = (tableName, conditions = {}) => {...}
exports.remove = (tableName, conditions = {}, data = []) => {...}

And finally you can use this in you route handlers without cluttering your codebase:

const db = require("../db");

/**
 *
 */
exports.updateUser = async (req, res) => {
  try {
    console.log("[PUT] {api/v1/users}");
    const fields = {
      name: req.body.name,
      description: req.body.description,
      info: req.body.info
    };
    const userId = req.params.id;

    const conditions = { id: userId };
    const updatedUser = await db.updateOne("users", conditions, fields);

    if (updatedUser) {
      console.log(`team ${updatedUser.name} updated successfully`);
      return res.json(updatedUser);
    }
    res.status(404).json({ msg: "Bad request" });
  } catch (err) {
    console.error(err);
    res.status(500).send({ msg: "Server error" });
  }
};

Convenient utilities:

const Utils = {};
Utils.isObject = x => x !== null && typeof x === "object";
Utils.isObjEmpty = obj => Utils.isObject(obj) && Object.keys(obj).length === 0;