Javascript AST: print CallExpression or FunctionDeclaration

print-func.js

/* npm install acorn acorn-walk */
/* usage: nodejs print-func.js foo.js --call */

let mode  = 'name';
let index = process.argv.findIndex(function(e) { return e == "--call"});
if (index > 0) { process.argv.splice(index, 1); mode = 'call'; }

let filename = process.argv[2];
if (!filename) throw "file not found";

const acorn = require("acorn")
const walk  = require("acorn-walk")
const glob  = require("glob")
const path  = require("path")
const fs    = require("fs")

glob.sync("./prelude/*.js").forEach( function( file ) {
  require( path.resolve( file ) );
});

fs.readFile(filename, "utf8", (error, code) => {
  if (error) throw error;
  var ast = acorn.parse(code, {ecmaVersion: 8});

  walk.simple(ast, {
    CallExpression(node) {
      if (mode == 'call') {
        var name = node.callee.name;
        if (name) console.log(name); // skip 'undefined'
      }
    },
    FunctionDeclaration(node) {
      if (mode == 'name') {
        console.log(node.id.name)
      }
    }
  })
});