generate call graph from .js files

generate_callgraph_js_module

#!/usr/bin/env node

const fs = require('fs');
const path = require('path');
const parser = require('@babel/parser');
const traverse = require('@babel/traverse').default;

// Input files from command-line arguments
const inputFiles = process.argv.slice(2);

// Data structures
const functionsByFile = {};
const calls = [];
const topLevelCallsByFile = {};

function getFunctionName(node, parent) {
    if (node.id && node.id.name) return node.id.name;
    if (parent.type === 'VariableDeclarator' && parent.id.name) return parent.id.name;
    return null;
}

function parseFile(filePath) {
    const code = fs.readFileSync(filePath, 'utf8');
    const ast = parser.parse(code, {
        sourceType: 'module',
        plugins: ['jsx', 'typescript']
    });

    const fileName = path.basename(filePath);
    functionsByFile[fileName] = [];
    topLevelCallsByFile[fileName] = [];

    traverse(ast, {
        enter(pathNode) {
            const node = pathNode.node;

            // Function declaration or arrow function assignment
            if (
                node.type === 'FunctionDeclaration' ||
                (node.type === 'VariableDeclarator' &&
                    (node.init?.type === 'ArrowFunctionExpression' || node.init?.type === 'FunctionExpression'))
            ) {
                const funcName = getFunctionName(node, pathNode.parent);
                if (funcName) {
                    functionsByFile[fileName].push(funcName);
                }
            }

            // Function call expression
            if (node.type === 'CallExpression' && node.callee.type === 'Identifier') {
                const calleeName = node.callee.name;
                const enclosingFunc = pathNode.getFunctionParent();

                if (enclosingFunc) {
                    const enclosingId = enclosingFunc.node.id || enclosingFunc.parent?.id;
                    const enclosingName = enclosingId ? enclosingId.name : null;
                    if (enclosingName) {
                        calls.push({
                            from: enclosingName,
                            to: calleeName,
                            file: fileName
                        });
                    }
                } else {
                    // Track top-level calls
                    topLevelCallsByFile[fileName].push({
                        caller: fileName,
                        callee: calleeName
                    });
                }
            }
        }
    });
}

// Parse each file
inputFiles.forEach(parseFile);

// Generate DOT file
console.log("digraph CallGraph {");
console.log("  rankdir=LR;");
console.log("  node [shape=box, style=filled, fillcolor=\"#f9f9f9\"];");

// Create clusters for each file
for (const [file, funcs] of Object.entries(functionsByFile)) {
    const clusterId = file.replace(/[^\w]/g, '_');
    console.log(`  subgraph cluster_${clusterId} {`);
    console.log(`    label = "${file}";`);
    console.log("    style=filled;");
    console.log("    color=lightgrey;");
    funcs.forEach(fn => {
        console.log(`    "${fn}";`);
    });
    console.log("  }");
}

// Add call relationships between functions
calls.forEach(({ from, to, file }) => {
    const targetExists = Object.values(functionsByFile).some(funcs => funcs.includes(to));
    if (targetExists) {
        console.log(`  "${from}" -> "${to}";`);
    }
});

// Add top-level call relationships
for (const [file, topCalls] of Object.entries(topLevelCallsByFile)) {
    if (topCalls.length > 0) {
        const clusterId = file.replace(/[^\w]/g, '_');
        console.log(`  subgraph cluster_${clusterId}_top {`);
        console.log(`    label = "${file} (top-level)";`);
        console.log("    style=filled;");
        console.log("    color=lightblue;");
        console.log(`    "${file}" [shape=ellipse];`);
        console.log("  }");

        topCalls.forEach(({ callee }) => {
            const targetExists = Object.values(functionsByFile).some(funcs => funcs.includes(callee));
            if (targetExists) {
                console.log(`  "${file}" -> "${callee}";`);
            }
        });
    }
}

console.log("}");

Example usage:

generate_callgraph_js_module data.js domain.js business.js index.js | dot -Tpng -o callgraph.png