Cleaning generated files from ts/less compilation

gulpfile.js

const cleanGeneratedFilesBasedOn = (mapFileExtension, sourceFileExtension, otherExtensionsToDelete) => {
    const debug = true;
    const startTime = new Date().getTime();
    if (!Array.isArray(otherExtensionsToDelete)) {
        otherExtensionsToDelete = [];

    }
    const pattern = '{,!(node_modules)/**/}*' + mapFileExtension;
    return glob(pattern, (err, files) => {
        let toDelete = [];

        for (let file of files) {
            const siblingsToDelete = [];
            const folder = path.dirname(file);
            const filename = path.basename(file).slice(0, -mapFileExtension.length);
            const srcFilePath = `${folder}/${filename}${sourceFileExtension}`
            const hasSiblingSrcFile = fs.existsSync(srcFilePath);

            if (hasSiblingSrcFile) {
                siblingsToDelete.push(`${folder}/${filename}${mapFileExtension}`);
            }

            for (let otherExtensionToDelete of otherExtensionsToDelete) {
                const otherPath = `${folder}/${filename}${otherExtensionToDelete}`
                const hasSiblingFileToDelete = fs.existsSync(otherPath);
                if (hasSiblingSrcFile && hasSiblingFileToDelete) {
                    siblingsToDelete.push(otherPath);
                }
            }

            if (debug) {
                console.debug(`Mapfile considered: ${file} (folder: ${folder}, filename: ${filename})`);
                console.debug(`> Potential source file ${srcFilePath}: ${hasSiblingSrcFile ? 'found' : 'not found'}`);
                console.debug(`> Files to delete: ${siblingsToDelete.length}`);
                for (let pathToDelete of siblingsToDelete) {
                    console.debug(`  - ${pathToDelete}`);
                }
            }

            toDelete = toDelete.concat(siblingsToDelete);
        }

        return del(toDelete, {dryRun: debug})
            .then(deletedPaths => console.debug(`${deletedPaths.length} generated files from typescript compilation deleted in ${new Date().getTime() - startTime} ms`));
    });
}

gulp.task('typescript:clean', () => {
    return cleanGeneratedFilesBasedOn('.js.map', '.ts', ['.js']);
});

gulp.task('less:clean', () => {
    return cleanGeneratedFilesBasedOn('.css.map', '.less');
});

Situation when this snippet applies

• you are compiling typescript, less, scss files into js, css files in the same folder
• and your compilation is creating map files
• and you want to clean generated files without deleting other files

Important notes:

• When additional extensions are given, the source file (.ts, .less) has to be there in order to delete the file with this additional extension. For example, let's say you had a gulpfile.ts which generated gulpfile.js and gulpfile.js.map. Then you decide to abandon the ts and only keep a js file, but you didn't remove the .js.map. Without this condiction, the task would have removed the js file, event if it's now your original source file.

Receipe for typescript compilation:

• look for .js.map files
• when you find one having in the same folder a file with the same name but the .ts and .js enxtensions, you can consider .js.map and .js files as generated by the compilation and remove them

Example:

// content of a folder
--- filename ---               --- description ---              --- will be deleted ? ---
a.component.ts            // original source file                      no
a.component.js            // generated file                            yes
a.component.js.map        // generated file                            yes
a.component.less          // original source file                      no
a.component.css           // generated file                            yes
a.component.css.map       // generated file                            yes
a.module.js               // another file                              no

Outputs

• when debug mode is set to true, each map file will outputs something like:

Mapfile considered: registrars.js.map (folder: ., filename: registrars)
> Potential source file ./registrars.ts: found
> Files to delete: 2
  - ./registrars.js.map
  - ./registrars.js

... and files won't be really removed

• when debug mode is set to false, we only prints a summary once all the files are removed

[16:17:59] Using gulpfile D:\code\portal\api\static\public\gulpfile.js
[16:17:59] Starting 'typescript:clean'...
[16:17:59] Finished 'typescript:clean' after 3.3 ms
1900 generated files from typescript compilation deleted in 568 ms