Eslint Standalone in Azure Devops Build task

I have created a standalone tool that can run Eslint from the commandline. The tool is a Node.js application build with Pkg as a node10-win application, built as a standalone EXE file executable. You can find the repository here:

https://github.com/toreaurstadboss/eslint-standalone

Here you can also alter the application to your needs, if necessary. The application is available as a Npm package or a Nuget package on the official repos (npmjs.org and nuget.org) This article will focus on the use of the application via Nuget and activating the tool in Azure devops. First off make sure you add the official Nuget repo to your Nuget.config file like this:

<?xml version="1.0" encoding="utf-8"?>
<configuration>
  <packageRestore>
    <add key="enabled" value="True" />
  </packageRestore>
  <activePackageSource>
    <!-- some other nuget repo in addition if desired -->
  </activePackageSource>
  <packageSources>
    <clear />
    <!-- some other nuget repo in addition if desired -->
    <add key="Nuget official repo" value="https://nuget.org/api/v2/" />
  </packageSources>
</configuration>

Now you can add a packagereference to the EslintStandalone.Cli tool in the .csproj project file (or .vbproj if you use Visual Basic) like this:

<PackageReference Include="EslintStandalone.Cli" Version="1.1.0" GeneratePathProperty="true" />

Also add the following copy step to copy the standalone.exe tool within the Nuget package out to the bin folder of your project: <ItemGroup> <Content Include="$(PkgEslintStandalone_Cli)\eslint-standalone.exe"> <CopyToOutputDirectory>Always</CopyToOutputDirectory> </Content> </ItemGroup> This is possible since you use GeneratePathProperty set to true and we refer the folder of the nuget on disk like $(PkgEslintStandalone_Cli). The Nuget pakage is called EsLintStandalone.Cli. We replace '.' with '_' and we prefix always the variable to point to the nuget folder with Pkg and we reference the entire package with the $() expression. The next step is to add the execution of the tool in Azure Devops like a task. You can either define a single task or a Task group. I like task groups, since we then can easily share task among projects. The following command should be added:

dir
echo Starting Eslint tool to analyzing for compability issues in Javascript files
cd Source\SomeProject\bin
echo Current folder
dir *.exe
move eslint-standalone.exe ..
cd ..
echo Navigated to root folder of SomeProject. Starting the eslint-standalone tool. 
eslint-standalone.exe

Here we copy the standalone tool a level down to the root of the project, parent folder of bin folder. Here we usually have our target files, which will be Javascript files in our project with such files (e.g. a MVC project or other web projects usually). Finally we must supply a .eslintrc.js file, a config file for Eslint. At my work, I have customers that uses Internet Explorer 11. So I check for Ecmascript 5 compability. This tool can handle such as scenario. The following .eslintrc.js such suffice:

module.exports = {
    "plugins": ["ie11"],
    "env": {
      "browser": true,
      "node": true,
      "es6": false
    },
    "parserOptions": {
      "ecmaVersion": 5,
    },
    "rules": {
      "ie11/no-collection-args": ["error"],
      "ie11/no-for-in-const": ["error"],
      //"ie11/no-loop-func": ["warn"],
      "ie11/no-weak-collections": ["error"],
      "curly": ["off"]
    }
};

//A list of rules that can be applied is here: https://eslint.org/docs/rules/
//The rules can have the following severity in EsLint: "warn", "error" and "off".

https://eslint.org/docs/rules/ You can find Eslint rules at the link above. You can set the error level to either 'warn' or' 'error' or 'off'. https://eslint.org/docs/user-guide/configuring If you want to use the tool in a Npm based project, you can see the Npm page here: https://www.npmjs.com/package/eslint-standalone npm i eslint-standalone I got two version of the tool. Version 1.1. is recommended, as you must supply a .eslintrc.js file and have control over how the linting is done. Version 1.2. supplies a .eslintrc.js in the same folder as the tool with ES5 support detection as shown above included (.eslintrc.js file is bundled together). The tool itself is quite simple code in Node.js:

#!/usr/bin/env node

const CLIEngine = require("eslint").CLIEngine;
const minimist = require("minimist");
const path = require("path");
const chalk = require("chalk");
const eslintPluginCompat = require("eslint-plugin-compat");
const eslintIe11 = require("eslint-plugin-ie11");
const fs = require("fs");
const { promisify } = require("util");

const fsAccessAsync = promisify(fs.access);

var runEsLint = function(baseConfig, args) {
  const cli = new CLIEngine({ baseConfig });

  let filesDir = [];

  if (args.dir) {
    // Dir can be a string or an array, we do a preprocessing to always have an array
    filesDir = []
      .concat(args.dir)
      .map((item) => path.resolve(process.cwd(), item));
  } else {
    filesDir = ["./."];
  }

  console.log(`> eslint is checking the following dir: ${filesDir}`);

  const report = cli.executeOnFiles(filesDir);

  if (report.errorCount > 0) {
    const formatter = cli.getFormatter();

    console.log(
      chalk.bold.redBright(`> eslint has found ${report.errorCount} error(s)`)
    );
    console.log(formatter(report.results));

    process.exitCode = 1; //eslint errors encountered means the process should exit not with exit code 0.

    return;
  }
  console.log(chalk.bold.greenBright("> eslint finished without any errors!"));
  process.env.exitCode = 0; //exit with success code

}

var tryLoadConfigViaKnownSystemFolder = function(){

  let configFileFound = null;
try {
  let knownHomeDirectoryOnOSes =
    process.env.HOME || process.env.HOMEPATH || process.env.USERPROFILE;
  let knownHomeDirectoryOnOSesNormalized = path.normalize(
    knownHomeDirectoryOnOSes + "/.eslintrc"
  );
  configPath = path.resolve(knownHomeDirectoryOnOSesNormalized);
  if (checkIfFileExistsAndIsAccessible(configPath)){
    configFileFound = true;
    errorEncountered = false;
  }

} catch (error) {
  errorEncountered = true;
  console.error(error);  
  process.exitCode = 1; //signal an error has occured. https://stackoverflow.com/questions/5266152/how-to-exit-in-node-js
  return configFileFound;
}

};


var checkIfFileExistsAndIsAccessible = function(configPathFull) {
  try {
   fs.accessSync(configPathFull, fs.F_OK);
  return true;
  }
  catch (Error){
    return false;
   }  
}


var tryLoadFileInDirectoryStructure = function(curDir){

  let configFullPathFound = null;
  for (let i = 0; i < 100; i++) {
    try {
      if (i > 0) {
        console.info("Trying lib folder of eslint-standalone: " + curDir);
        let oldCurDir = curDir;
        curDir = path.resolve(curDir, ".."); //parent folder
        if (oldCurDir == curDir) {
          //at the top of media disk volume - exit for loop trying to retrieve the .eslintrc.js file from parent folder
          console.info(
            "It is recommended to save an .eslintrc.js file in the folder structure where you run this tool."
          );
          break;
        }
      }
      configPath = path.join(curDir + "/.eslintrc.js");
      configPath = path.normalize(configPath);
      if (checkIfFileExistsAndIsAccessible(configPath)){
       baseConfig = require(configPath);
       errorEncountered = false;
       configFullPathFound = configPath;
       break; //exit the for loop
      }
    } catch (error) {
      process.stdout.write(".");
      errorEncountered = true;
    }
  }
  return configFullPathFound;
}

var inspectArgs = function(args) {
  let fix = false;

  console.log("Looking at provided arguments:");
  for (var i = 0; i < args.length; i++) {
    console.log(args[i]);
    if (args[i] === "--fix") {
      fix = true;
      console.log("Fix option provided: " + fix);
      console.warn("Fix is not supported yet, you must manually adjust the files."
      );
    }
  }
}


module.exports = (() => {
  const args = process.argv.slice(2);

  inspectArgs(args); 

  // Read a default eslint config
  //console.log("Dirname: " + __dirname);

  let configPath = "";
  let baseConfig = "";
  let errorEncountered = false;

  console.info("Trying to resolve .eslintrc.js file");

  console.info("Trying current working directory:", process.cwd());

  let curDir = process.cwd();

  let configFilefound = tryLoadFileInDirectoryStructure(curDir);
  
  if (configFilefound === null) {
   curDir = __dirname;
   configFilefound = tryLoadFileInDirectoryStructure(curDir);
  }

  // try {
  //   configPath = path.join(curDir + "/.eslintrc.js");
  //   configPath = path.normalize(configPath);
  //   baseConfig = require(configPath);

  //   console.info("Found config file in current working folder");

  //   errorEncountered = false;
  //   configFilefound = baseConfig !== "";
  // } catch (error) {
  //   //ignore error handling for now at working folder
  //   configFilefound = false;
  // }

  // if (!configFilefound) {
  //   curDir = __dirname;

  //   for (let i = 0; i < 100; i++) {
  //     try {
  //       if (i > 0) {
  //         console.info("Trying lib folder of eslint-standalone: " + curDir);
  //         let oldCurDir = curDir;
  //         curDir = path.resolve(curDir, ".."); //parent folder
  //         if (oldCurDir == curDir) {
  //           //at the top of media disk volume - exit for loop trying to retrieve the .eslintrc.js file from parent folder
  //           console.info(
  //             "It is recommended to save an .eslintrc.js file in the folder structure where you run this tool."
  //           );
  //           break;
  //         }
  //       }
  //       configPath = path.join(curDir + "/.eslintrc.js");
  //       configPath = path.normalize(configPath);
  //       baseConfig = require(configPath);
  //       errorEncountered = false;
  //       break; //exit the for loop
  //     } catch (error) {
  //       process.stdout.write(".");
  //       errorEncountered = true;
  //     }
  //   }
  // }

  // Check if the path to a client config was specified
  if (args.conf) {
    if (Array.isArray(args.conf)) {
      const error = chalk.bold.redBright(
        `> eslint requires a single config file`
      );
      errorEncountered = true;
      console.warn(error);
    }

    try {
      configPath = path.resolve(process.cwd(), args.conf);
      baseConfig = require(configPath);
      errorEncountered = false;
    } catch (error) {
      errorEncountered = true;
      console.log(error);
    }
  }

  if (errorEncountered === true) {
    configFileFound = tryLoadConfigViaKnownSystemFolder();
    if (configFileFound !== null) {
      baseConfig = `{
        "extends": "${configPath}"         
      }`;    
    }
    // try {
    //   let knownHomeDirectoryOnOSes =
    //     process.env.HOME || process.env.HOMEPATH || process.env.USERPROFILE;
    //   let knownHomeDirectoryOnOSesNormalized = path.normalize(
    //     knownHomeDirectoryOnOSes + "/.eslintrc"
    //   );
    //   configPath = path.resolve(knownHomeDirectoryOnOSesNormalized);
    

    //   errorEncountered = false;
    // } catch (error) {
    //   errorEncountered = true;
    //   console.error(error);
    //   process.exitCode = 1; //signal an error has occured. https://stackoverflow.com/questions/5266152/how-to-exit-in-node-js
    //   return;
    // }
  }

  console.log(`> eslint has loaded config from: ${configFilefound}`);

  runEsLint(baseConfig, args);

  // console.log('base config: ');
  // console.log(baseConfig);

  // const cli = new CLIEngine({ baseConfig });

  // let filesDir = [];

  // if (args.dir) {
  //   // Dir can be a string or an array, we do a preprocessing to always have an array
  //   filesDir = []
  //     .concat(args.dir)
  //     .map((item) => path.resolve(process.cwd(), item));
  // } else {
  //   filesDir = ["./."];
  // }

  // console.log(`> eslint is checking the following dir: ${filesDir}`);

  // const report = cli.executeOnFiles(filesDir);

  // if (report.errorCount > 0) {
  //   const formatter = cli.getFormatter();

  //   console.log(
  //     chalk.bold.redBright(`> eslint has found ${report.errorCount} error(s)`)
  //   );
  //   console.log(formatter(report.results));

  //   process.exitCode = 1; //eslint errors encountered means the process should exit not with exit code 0.

  //   return;
  // }
  // console.log(chalk.bold.greenBright("> eslint finished without any errors!"));
  // process.env.exitCode = 0; //exit with success code
})();