convert.js

// Importing required modules
const sharp = require('sharp');
const fs = require('fs');
const path = require('path');

// Define input and output directories
const inputDirectory = './input';
const outputDirectory = './output';

// Configuration object with image size, scale, and format options
const config = {
    sizes: [1024, 2048, 4096], // array of image widths to resize to
    scales: [1, 0.5, 0.25], // array of scales to resize the image by
    formats: ['png', 'jpg', 'webp'] // array of image formats to save the resized images as
};

// Read the directory to get a list of files
fs.readdir(inputDirectory, (err, files) => {
    if (err) {
        // Log the error and return
        console.error(err);
        return;
    }

    // Iterate through each file
    files.forEach(file => {
        // Build the input file path
        const inputFile = path.join(inputDirectory, file);
        // Get the base file name
        const baseFileName = path.parse(file).name;
        // Build the output folder path
        const outputFolder = path.join(outputDirectory, baseFileName);

        // Check if the output folder exists, if not create it
        if (!fs.existsSync(outputFolder)) {
            fs.mkdirSync(outputFolder);
        } else {
            // If the output folder exists, remove it and recreate it
            fs.rmdirSync(outputFolder, { recursive: true });
            fs.mkdirSync(outputFolder);
        }

        // Use the sharp module to get metadata from the input file
        sharp(inputFile)
            .metadata()
            .then(metadata => {
                // Store the original width of the image
                const originalWidth = metadata.width;

                // Iterate through each format in the config
                config.formats.forEach(format => {
                    // Iterate through each size in the config
                    config.sizes.forEach(size => {
                        // Build the output file path
                        const outputFile = path.join(
                            outputFolder,
                            `${baseFileName}-${size}.${format}`
                        );

                        // Use the sharp module to resize the image and save it to the output file path
                        sharp(inputFile)
                            .resize({ width: size })
                            .toFormat(format)
                            .toFile(outputFile, (error, info) => {
                                if (error) {
                                    // Log the error
                                    console.error(error);
                                } else {
                                    // Log success message
                                    console.log(
                                        `Successfully converted ${inputFile} to ${outputFile} in ${format} format`
                                    );
                                }
                            });
                    });

                    // Iterate through each scale in the config
                    config.scales.forEach(scale => {
                        // Build the output file path
                        const outputFile = path.join(
                            outputFolder,
                            `${baseFileName}-${scale}x.${format}`
                        );

                        // Use the sharp module to resize the image and save it to the output file path
                        sharp(inputFile)
                            .resize({ width: Math.round(originalWidth * scale) })
                            .toFormat(format)
                            .toFile(outputFile, (error, info) => {
                                if (error) {
                                    console.error(error);
                                } else {
                                    console.log(
                                        `Successfully converted ${inputFile} to ${outputFile} in ${format} format`
                                    );
                                }
                            });
                    });
                });
            })
            .catch(error => {
                console.error(error);
            });
    });
});