'usage' code doesn't work without modification

[matteliot]

Grabbed the code, made a file that was a direct copy from the README Usage section.

It can't load "sht31".

Is it intended that the usage code ought to be usable without any modifications? If not, you might want to call that out.

[alwint3r]

It should work without any modification at best case. You might only need to change the I2C address or the I2C bus number that given to the constructor.

Could you elaborate me how you use this library?

[matteliot]

If you take the example code from readme, put it into a file and try to run it, it errors out because SHT isn't defined.

I'm using node 7.9, but I don't think it matters in this case.

"use strict";

const test= require("./index");

//const SHT31 = require(`sht31`); **//ORIGINAL CODE with error**
const SHT31 = require(`./index`).SHT31; **//this one works**
const sht31 = new SHT31(0x44, 1); // address: 0x44, device = /dev/i2c-1

sht31
  .init()
  .then(() => sht31.readSensorData())
  .then((data) => {
    console.log(data);
  })
  .catch((err) => {
    // ...
    // Handle errors
console.log("Error: " + err);
  });

here's the error you'd get with the original code:

/projects/sht31-node/src # node origRun.js 
module.js:472
    throw err;
    ^

Error: Cannot find module 'sht31'
    at Function.Module._resolveFilename (module.js:470:15)
    at Function.Module._load (module.js:418:25)
    at Module.require (module.js:498:17)
    at require (internal/module.js:20:19)
    at Object.<anonymous> (/projects/sht31-node/src/origRun.js:1:77)
    at Module._compile (module.js:571:32)
    at Object.Module._extensions..js (module.js:580:10)
    at Module.load (module.js:488:32)
    at tryModuleLoad (module.js:447:12)
    at Function.Module._load (module.js:439:3)

[alwint3r]

Alright, I think the way you use this library is kinda wrong in some way. The code in the "usage" section of README is assuming that you have installed the module as a depencency. I also said in another issue of yours, that this index.js file should not be run directly.

Your stacktrace said that node can not find this module in your system. Error: Cannot find module 'sht31'

So, I think this is the right & "common" way:

• You create a folder for your project, e.g reading_sht31.
• Then, inside that project folder you initialize the package.json by running npm init -y
• Then, install this library by running npm install sht31 --save.
• Then, you create a .js file inside the project directory, e.g read_sensor.js and you can copy-pase the code from usage section of README.
• You might want to change the I2C address of SHT31 sensor (first argument) and I2C bus number (second argument) of the constructor. In Raspberry Pi 3, the default I2C bus number is 1. For the SHT31 I2C address, it should be 0x44. If you're having problem with reading from I2C on a Raspberry Pi, please see this link.
• If everything's fine, you can run the read_sensor.js program.

In the end, your code is working although I think it is not the preferred way of using a node module.