find files by extension, *.html under a folder in nodejs

I'd like to find all *.html files in src folder and all its sub folders using nodejs. What is the best way to do it?

var folder = '/project1/src';
var extension = 'html';
var cb = function(err, results) {
   // results is an array of the files with path relative to the folder
   console.log(results);

}
// This function is what I am looking for. It has to recursively traverse all sub folders. 
findFiles(folder, extension, cb);

I think a lot developers should have great and tested solution and it is better to use it than writing one myself.

node.js, recursive simple function:

var path = require('path'),
fs = require('fs');

function fromDir(startPath, filter) {

    //console.log('Starting from dir '+startPath+'/');

    if (!fs.existsSync(startPath)) {
        console.log("no dir ", startPath);
        return;
    }

    var files = fs.readdirSync(startPath);
    for (var i = 0; i < files.length; i++) {
        var filename = path.join(startPath, files[i]);
        var stat = fs.lstatSync(filename);
        if (stat.isDirectory()) {
            fromDir(filename, filter); //recurse
        } else if (filename.endsWith(filter)) {
            console.log('-- found: ', filename);
        };
    };
};

fromDir('../LiteScript', '.html');

add RegExp if you want to get fancy, and a callback to make it generic.

var path = require('path'),
fs = require('fs');

function fromDir(startPath, filter, callback) {

    //console.log('Starting from dir '+startPath+'/');

    if (!fs.existsSync(startPath)) {
        console.log("no dir ", startPath);
        return;
    }

    var files = fs.readdirSync(startPath);
    for (var i = 0; i < files.length; i++) {
        var filename = path.join(startPath, files[i]);
        var stat = fs.lstatSync(filename);
        if (stat.isDirectory()) {
            fromDir(filename, filter, callback); //recurse
        } else if (filter.test(filename)) callback(filename);
    };
};

fromDir('../LiteScript', /\.html$/, function(filename) {
    console.log('-- found: ', filename);
});

i like using the glob package:

const glob = require('glob');

glob(__dirname + '/**/*.html', {}, (err, files)=>{
  console.log(files)
})

What, hang on?! ... Okay ya, maybe this makes more sense to someones else too.

[nodejs 7 mind you]

fs = import('fs');
let dirCont = fs.readdirSync( dir );
let files = dirCont.filter( function( elm ) {return elm.match(/.*\.(html?)/ig);});

Do whatever with regex make it an argument you set in the function with a default etc.

Based on Lucio's code, I made a module. It will return an away with all the files with specific extensions under the one. Just post it here in case anybody needs it.

var path = require('path'), 
    fs   = require('fs');


/**
 * Find all files recursively in specific folder with specific extension, e.g:
 * findFilesInDir('./project/src', '.html') ==> ['./project/src/a.html','./project/src/build/index.html']
 * @param  {String} startPath    Path relative to this file or other file which requires this files
 * @param  {String} filter       Extension name, e.g: '.html'
 * @return {Array}               Result files with path string in an array
 */
function findFilesInDir(startPath,filter){

    var results = [];

    if (!fs.existsSync(startPath)){
        console.log("no dir ",startPath);
        return;
    }

    var files=fs.readdirSync(startPath);
    for(var i=0;i<files.length;i++){
        var filename=path.join(startPath,files[i]);
        var stat = fs.lstatSync(filename);
        if (stat.isDirectory()){
            results = results.concat(findFilesInDir(filename,filter)); //recurse
        }
        else if (filename.indexOf(filter)>=0) {
            console.log('-- found: ',filename);
            results.push(filename);
        }
    }
    return results;
}

module.exports = findFilesInDir;

You can use Filehound to do this.

For example: find all .html files in /tmp:

const Filehound = require('filehound');

Filehound.create()
  .ext('html')
  .paths("/tmp")
  .find((err, htmlFiles) => {
    if (err) return console.error("handle err", err);

    console.log(htmlFiles);
});

For further information (and examples), check out the docs: https://github.com/nspragg/filehound

Disclaimer: I'm the author.

I have looked at the above answers and have mixed together this version which works for me:

function getFilesFromPath(path, extension) {
    let files = fs.readdirSync( path );
    return files.filter( file => file.match(new RegExp(`.*\.(${extension})`, 'ig')));
}

console.log(getFilesFromPath("./testdata", ".txt"));

This test will return an array of filenames from the files found in the folder at the path ./testdata. Working on node version 8.11.3.

The following code does a recursive search inside ./ (change it appropriately) and returns an array of absolute file names ending with .html

var fs = require('fs');
var path = require('path');

var searchRecursive = function(dir, pattern) {
  // This is where we store pattern matches of all files inside the directory
  var results = [];

  // Read contents of directory
  fs.readdirSync(dir).forEach(function (dirInner) {
    // Obtain absolute path
    dirInner = path.resolve(dir, dirInner);

    // Get stats to determine if path is a directory or a file
    var stat = fs.statSync(dirInner);

    // If path is a directory, scan it and combine results
    if (stat.isDirectory()) {
      results = results.concat(searchRecursive(dirInner, pattern));
    }

    // If path is a file and ends with pattern then push it onto results
    if (stat.isFile() && dirInner.endsWith(pattern)) {
      results.push(dirInner);
    }
  });

  return results;
};

var files = searchRecursive('./', '.html'); // replace dir and pattern
                                                // as you seem fit

console.log(files);

You can use OS help for this. Here is a cross-platform solution:

1. The bellow function uses ls and dir and does not search recursively but it has relative paths

var exec = require('child_process').exec;
function findFiles(folder,extension,cb){
	var command = "";
	if(/^win/.test(process.platform)){
		command = "dir /B "+folder+"\\*."+extension;
	}else{
		command = "ls -1 "+folder+"/*."+extension;
	}
	exec(command,function(err,stdout,stderr){
		if(err)
			return cb(err,null);
		//get rid of \r from windows
		stdout = stdout.replace(/\r/g,"");
		var files = stdout.split("\n");
		//remove last entry because it is empty
		files.splice(-1,1);
		cb(err,files);
	});
}

findFiles("folderName","html",function(err,files){
	console.log("files:",files);
})

2. The bellow function uses find and dir, searches recursively but on windows it has absolute paths

var exec = require('child_process').exec;
function findFiles(folder,extension,cb){
	var command = "";
	if(/^win/.test(process.platform)){
		command = "dir /B /s "+folder+"\\*."+extension;
	}else{
		command = 'find '+folder+' -name "*.'+extension+'"'
	}
	exec(command,function(err,stdout,stderr){
		if(err)
			return cb(err,null);
		//get rid of \r from windows
		stdout = stdout.replace(/\r/g,"");
		var files = stdout.split("\n");
		//remove last entry because it is empty
		files.splice(-1,1);
		cb(err,files);
	});
}

findFiles("folder","html",function(err,files){
	console.log("files:",files);
})

Can't add a comment because of reputation, but notice the following:

Using fs.readdir or node-glob to find a wildcard set of files in a folder of 500,000 files took ~2s. Using exec with DIR took ~0.05s (non recursive) or ~0.45s (recursive). (I was looking for ~14 files matching my pattern in a single directory).

So far, I have failed to find any nodejs implementation which uses low level OS wildcard searching for efficiency. But the above DIR/ls based code works wonderfully in windows in terms of efficiency. linux find, however, will likely be very slow for large directories.

Take a look into file-regex

let findFiles = require('file-regex')
let pattern = '\.js'

findFiles(__dirname, pattern, (err, files) => {  
   console.log(files);
})

This above snippet would print all the js files in the current directory.

Install

you can install this package walk-sync by

yarn add walk-sync

Usage

const walkSync = require("walk-sync");
const paths = walkSync("./project1/src", {globs: ["**/*.html"]});
console.log(paths);   //all html file path array

my two pence, using map in place of for-loop

var path = require('path'), fs = require('fs');

var findFiles = function(folder, pattern = /.*/, callback) {
  var flist = [];
  
  fs.readdirSync(folder).map(function(e){ 
    var fname = path.join(folder, e);
    var fstat = fs.lstatSync(fname);
    if (fstat.isDirectory()) {
      // don't want to produce a new array with concat
      Array.prototype.push.apply(flist, findFiles(fname, pattern, callback)); 
    } else {
      if (pattern.test(fname)) {
        flist.push(fname);
        if (callback) {
          callback(fname);
        }
      }
    }
  });
  return flist;
};

// HTML files   
var html_files = findFiles(myPath, /\.html$/, function(o) { console.log('look what we have found : ' + o} );

// All files
var all_files = findFiles(myPath);

I just noticed, you are using sync fs methods, that might block you application, here is a promise-based async way using async and q, you can execute it with START=/myfolder FILTER=".jpg" node myfile.js, assuming you put the following code in a file called myfile.js:

Q = require("q")
async = require("async")
path = require("path")
fs = require("fs")

function findFiles(startPath, filter, files){
    var deferred;
    deferred = Q.defer(); //main deferred

    //read directory
    Q.nfcall(fs.readdir, startPath).then(function(list) {
        var ideferred = Q.defer(); //inner deferred for resolve of async each
        //async crawling through dir
        async.each(list, function(item, done) {

            //stat current item in dirlist
            return Q.nfcall(fs.stat, path.join(startPath, item))
                .then(function(stat) {
                    //check if item is a directory
                    if (stat.isDirectory()) {
                        //recursive!! find files in subdirectory
                        return findFiles(path.join(startPath, item), filter, files)
                            .catch(function(error){
                                console.log("could not read path: " + error.toString());
                            })
                            .finally(function() {
                                //resolve async job after promise of subprocess of finding files has been resolved
                                return done();
                             });
                    //check if item is a file, that matches the filter and add it to files array
                    } else if (item.indexOf(filter) >= 0) {
                        files.push(path.join(startPath, item));
                        return done();
                    //file is no directory and does not match the filefilter -> don't do anything
                    } else {
                        return done();
                    }
                })
                .catch(function(error){
                    ideferred.reject("Could not stat: " + error.toString());
                });
        }, function() {
            return ideferred.resolve(); //async each has finished, so resolve inner deferred
        });
        return ideferred.promise;
    }).then(function() {
        //here you could do anything with the files of this recursion step (otherwise you would only need ONE deferred)
        return deferred.resolve(files); //resolve main deferred
    }).catch(function(error) {
        deferred.reject("Could not read dir: " + error.toString());
        return
    });
    return deferred.promise;
}


findFiles(process.env.START, process.env.FILTER, [])
    .then(function(files){
        console.log(files);
    })
    .catch(function(error){
        console.log("Problem finding files: " + error);
})

You can Edit this code to suit what you intend doing. I used the sync versions for the nodejs IO operations so that the results will be returned before node continues executing the next lines of code:

const fs = require('fs');
const path = require('path');
    
// Path to the directory(folder) to look into
const dirPath = path.resolve(`${__dirname}../../../../../tests_output`);
        
// Read all files with .html extension in the specified folder above
const filesList = fs.readdirSync(dirPath, (err, files) => files.filter((e) => path.extname(e).toLowerCase() === '.html'));
        
// Read the content of the first file with .txt extension in the folder
const data = fs.readFileSync(path.resolve(`${__dirname}../../../../../tests_output/${filesList[0]}`), 'utf8');

res.writeHead(200, { 'Content-Type': 'text/html' });
res.write(data);
return res.end();

To the myriad of possible solutions we can also add fs-jetpack library that is perfect for build-script purposes.

const jetpack = require("fs-jetpack");

// the sync way
const files = jetpack.find("my_project", { matching: "*.html" });
console.log(files);

// or the async way
jetpack.findAsync("my_project", { matching: "*.html" }).then(files => {
  console.log(files);
});

Old post but ES6 now handles this out of the box with the includes method.

let files = ['file.json', 'other.js'];

let jsonFiles = files.filter(file => file.includes('.json'));

console.log("Files: ", jsonFiles) ==> //file.json