scripts/queryRollupStats.js

"use strict";

/* eslint-disable no-console */

// This script queries a stats.json file generated by rollup-plugin-visualizer to find all reference paths to a specific module.
// This helps understand why a module is not being tree shaken from the bundle.
// Example: node queryRollupStats.js someModule.js

const fs = require("fs");
const path = require("path");
const chalk = require("chalk");

function stringToColorHash(str) {
    // Simple hash function
    let hash = 0;
    for (let i = 0; i < str.length; i++) {
        hash = str.charCodeAt(i) + ((hash << 5) - hash);
    }

    // Convert hash to 6-digit hexadecimal string
    let color = "#";
    for (let i = 0; i < 3; i++) {
        const value = (hash >> (i * 8)) & 0xff;
        color += value.toString(16).substring(-2);
    }

    return color;
}

function queryRollupStats(filter, maxDepth, statsFilePath) {
    if (!maxDepth) {
        maxDepth = Number.POSITIVE_INFINITY;
    }
    const { nodeMetas } = JSON.parse(fs.readFileSync(statsFilePath, "utf8"));
    const referenceStack = [];
    const seenStacks = new Set();

    function traverse(uid, depth) {
        const node = nodeMetas[uid];
        referenceStack.push(node.id);

        if (node.importedBy.length === 0 || depth >= maxDepth) {
            const stack = referenceStack.join(" -> ");
            if (!seenStacks.has(stack)) {
                seenStacks.add(stack);

                for (let reference of referenceStack) {
                    const folder = path.dirname(reference);
                    const file = path.basename(reference);
                    reference = chalk.hex(stringToColorHash(reference))(`${folder}/${chalk.bold(file)}`);
                    console.log(reference);
                }
                console.log();
            }
        } else {
            for (const importedBy of node.importedBy) {
                traverse(importedBy.uid, depth + 1);
            }
        }

        referenceStack.pop();
    }

    const matches = Object.entries(nodeMetas)
        .filter(([key, value]) => value.id.toLowerCase().includes(filter.toLocaleLowerCase()))
        .map(([key, value]) => key);

    matches.forEach((match) => traverse(match, 1));
}

if (require.main === module) {
    const [scriptPath, filter, maxDepth, statsFilePath = "stats.json"] = process.argv.slice(1);
    queryRollupStats(filter, maxDepth, statsFilePath);
}

module.exports = {
    queryRollupStats,
};