index.js

const core = require('@actions/core');
const fs = require('fs');
const path = require("path");


function walk_recursive(dir, exclude, callback) {
	fs.readdir(dir, function(err, files) {
		if (err) throw err;
		files.forEach(function(file) {
			var filepath = path.join(dir, file);
    if (!exclude.test(filepath)) {
        fs.stat(filepath, function(err,stats) {
          if (stats.isDirectory()) {
            walk_recursive(filepath, exclude, callback);
          } else if (stats.isFile()) {
            callback(filepath, stats);
          }
        });
      }
		});
	});
}

try {
    const regex = new RegExp(core.getInput('regex'), core.getInput('flags'));
    const replacement = core.getInput('replacement');
    const include = new RegExp(core.getInput('include'));
    const exclude = new RegExp(core.getInput('exclude'));
    const encoding = core.getInput('encoding');
    const start_path = core.getInput('path');

    walk_recursive(start_path, exclude, (file) => {
      if (include.test(file)){
        fs.readFile(file, encoding, function (err,data) {
          if (err) {
            return console.log(err);
          }
          var result = data.replace(regex, replacement);
          if (data != result) {
            console.log('Modifying ', file);
            fs.writeFile(file, result, encoding, function (err) {
            if (err) return core.setFailed(err);
           });
          }
        });
      }
    })
  } catch (error) {
    core.setFailed(error.message);
  }