Hi, I tried to use this library for the first time and immediately hit a very cryptic error:

ERROR in ./src/test.yaml (./node_modules/js-yaml-loader!./src/test.yaml)
Module Error (from ./node_modules/js-yaml-loader/index.js):
end of the stream or a document separator is expected at line 2, column 43:
     ... orts = doc.length <= 1 ? doc[0] : doc;
                                         ^
 @ ./src/index.js 1:0-46 3:12-16

Then webpack quits because js-yaml-loader didn't export a Buffer or String (yeah, since it failed.)

I've made a (hopefully) minimal test case and put it on this repo: https://github.com/unleashy/js-yaml-error-demo

As you can see in src/test.yaml, the file is empty. It doesn't seem to matter what you put in the yaml file, so I'm guessing it's some issue in the library itself; weirdly, "end of the stream or a document separator is expected" is a JS-YAML error message, so it's like JS-YAML is trying to parse the JS code... somehow? I don't know.

In any case, thanks!

The problem

When trying to load a file with multiple documents, I get the following error:

Module Error (from ./node_modules/js-yaml-loader/index.js): expected a single document in the stream, but found more

The file looks like something like this:

---
kind: example
apiVersion: v1
name: test
---
kind: example2
apiVersion: v1
name: test2
---
kind: example3
apiVersion: v1
name: test3

The solution

Ideally, I'd add a checker to count the documents, and if length > 1, then I'd invoke the safeLoadAll method instead of safeLoad. But since js-yaml doesn't export this counter function, would it be possible to replace safeLoad to safeLoadAll? I've tested and it would load both single and multiple documents in a file.

The change

const uneval = require('un-eval');
const { getOptions } = require('loader-utils');
const yaml = require('js-yaml');

module.exports = function(source) {
  this.cacheable && this.cacheable();

  try {
    const options = getOptions(this) || {};
    const safe = options.safe !== false;
    const res = safe ? yaml.safeLoadAll(source) : yaml.loadAll(source);
    return `module.exports = ${uneval(res)};`;
  } catch (err) {
    this.emitError(err);
    return null;
  }
};

When trying to import a date from a YAML file, like this:

education: 

    - name: University of Oklahoma
      instAbbr: UO
      location: Oklahoma City, OK
      degree: Bachelors of Information Technology
      degAbbr: BIT
      startDate: 2011-06-01
      endDate: 2014-01-01
      curriculum: 
              - DB1101 - Basic SQL
              - CS2011 - Java Introduction

Webpack spits out the error:

ERROR in ./import/EXAMPLE.yaml
Module parse failed: Invalid number (42:23)
You may need an appropriate loader to handle this file type.
|        degree: 'Bachelors of Information Technology',
|        degAbbr: 'BIT',
|        startDate: 2011-06-01T00:00:00.000Z,
|        endDate: 2014-01-01T00:00:00.000Z,
|        curriculum: [ 'DB1101 - Basic SQL', 'CS2011 - Java Introduction' ] } ],
 @ ./src/index.js 27:11-44
 @ multi (webpack)-dev-server/client?http://localhost:4000 ./src/index.js

Wrapping the dates in a quotes (to turn them into strings) works perfectly fine.

Attempting the same file with yaml-loader returns no issues, and imports the date as expected (i.e., as a DateTime object in the js object).

I am trying to read this yaml file:

function: !!js/function >
  function foobar() {
    return 'Wow! JS-YAML Rocks!';
  }

My _webpack.config.js:

    {
        test: /\.yaml$/,
        use: [{
            loader: 'js-yaml-loader',
            options: {
                safe: false
            }
        }]
    }

But i'm getting this error:
Module build failed: Error: Final loader didn't return a Buffer or String

I am used following way to read yaml file in React js
import React from 'react';
import logo from './logo.svg';
import './App.css';
import data from "./data.yml";
const title = data;

function App() {
return (

What is happening

Hey there! First of all, thank you for this great module!
Basically, everything works fine when I run yarn dev, but when I try to build the project with yarn build, the following error came:

yarn run v1.22.5
warning ..\..\..\package.json: No license field
$ next build
Failed to compile.

./core/components/Noun/words.ts:1:21
Type error: Cannot find module '../../content.yaml' or its corresponding type declarations.

>  1 | import content from "../../content.yaml";
     |                     ^
   3 |
   4 | const words = (content as {
   5 |     words: string[],
error Command failed with exit code 1.
info Visit https://yarnpkg.com/en/docs/cli/run for documentation about this command.

My files

package.json

{
    /* ... */
    "scripts": {
        "dev": "next dev",
        "build": "next build",
        "start": "next start"
    },
    "dependencies": {
        "js-yaml-loader": "^1.2.2",
        "mobx": "^6.1.7",
        "next": "10.0.6",
        "node": "^15.8.0",
        "react": "17.0.1",
        "react-dom": "17.0.1",
        "react-router-dom": "5.2.0",
        "styled-components": "5.2.1"
    },
    "devDependencies": {
        "@types/js-yaml": "^4.0.0",
        "@types/node": "^14.14.31",
        "@types/react": "17.0.1",
        "@types/styled-components": "^5.1.7",
        "typescript": "4.1.5"
    }
}

webpack.config.js

module: {
    rules: [{
        test: /\.ya?ml$/,
        use: 'js-yaml-loader',
    }]
}

next.config.js

module.exports = {
    webpack: function (config) {
        config.module.rules.push(
            {
                test: /\.ya?ml$/,
                use: 'js-yaml-loader',
            },
        )
        return config
    }
}

next-env.d.ts

/// <reference types="next" />
/// <reference types="next/types/global" />

Version 1.0.0 throws an error when trying to configure the loader without explicitly defining options with Webpack.

Fails with error "Cannot read property 'safe' of null".

Failing configuration:

rules: [
  {
    test: /\.yaml$/,
    use: 'js-yaml-loader'
  }
]

Working configuration:

rules: [
  {
    test: /\.yaml$/,
    use: [{
      loader: 'js-yaml-loader',
      options: {}
    }]
  }
]

Your package is vulnerable. could you apply a fix?

$ npm audit

json5  <2.2.2
Severity: high
Prototype Pollution in JSON5 via Parse Method - https://github.com/advisories/GHSA-9c47-m6qq-7p4h

node_modules/json5
  loader-utils  <=1.4.2
  Depends on vulnerable versions of json5
  node_modules/loader-utils
    js-yaml-loader  >=1.0.0
    Depends on vulnerable versions of loader-utils
    node_modules/js-yaml-loader

Upgrading https://www.npmjs.com/package/loader-utils should fix the issue:

npm install loader-utils@latest

I'm currently using js-yaml-loader to load my credentials from /config/secrets.yml but when I'm testing it using Jest.

image_handler.js

import placeholder from "../assets/images/placeholder.jpg";
import secrets from 'js-yaml-loader!../config/secrets.yml';
const config = secrets[process.env.NODE_ENV];

const parseImages = (images) => {
  var poiImages = [];
  if (images && images.length > 0 && images[0] != null) {
    for (let image of images) {
      var url = image.url || `${config.BASE_URL}/media/v1/download/uuid/${image.uuid}?apikey=${config.TIH_KEY}`;
      poiImages.push(url);
    }
  } else {
    poiImages.push(placeholder);
  }
  return poiImages;
}

export default {
  parseImages
};

I'm getting Cannot find module 'js-yaml-loader!../config/secrets.yml' from 'image_handler.js'