walker4folder

Walker4Folder

1.0.2

Tree walker for folders (Walker4Folder) with recursive runs over subdirectories. The walker4folder can be used to perform specific task like search and replace on a regular basis on a specific directory. On a Linux system the walker4folder can be used to perform standard task in a CronJob or for update HTML pages to import a new version of an updated library.

Installation

You you install walker4folder in your existing NodeJS project or create you own repository for a specific search and replace task in folder and subfolder

Installation for an exiting Repository

If you have already a repository in which you want to use the walker4folder just call the npm install:

npm install walker4folder

Create a new Repository

If you do not have a repository and you just want create script that searches files (recursively) into subdirectory and do something with some or all files, then perform the following steps for installation fpr your computer or operating system. The following commands are performed on shell/terminal:

• Create a new directory e.g. my_walker/ e.g. with mkdir my_walker
• Change to that directory with cd my_walker
• Initialize repository with npm init and fill the variables. After init you will have a package.json for your directory my_walker.
• Install the package with npm install walker4folder
• Create a main NodeJS script index.js in the repository.

const w4f = require('walker4folder');
w4f.walker4folder();
w4f.save_scanned();

The script above scans the current directory and all subdirectories and saves all found files and folders in the file scanned_file.json. You can create more than one walker4folder for different tasks and different folders.

Usage

Create a file e.g. my_walker.js and enter one of the following code options according to your requirements of the walker.

Start the Walker4Folder

Assuming you have at least one script in your repository in which the walker4folder was install. The default script should be index.js. Then you can start the search and replace for a specific folder by running the script with. node index.js If no directory parameter is provided to the walker4folder then the current directory will be scanned form which the script was called.

Scanned the current directory

Now we look into a script and explain how the walker4folder script can be The function walker4folder runs over the current directory with a call without parameter.

const w4f = require('walker4folder');
w4f.walker4folder();
w4f.save_scanned();

The function save_scanned() stores the scanned folders and files into a JSON for further processing. The JSON file would look like this:

{
    "dirs": [
        "libs"
    ],
    "files": [
        "package-lock.json",
        "package.json",
        "scanned_file.json",
        "libs/loadsave.js",
        "libs/main.js"
    ]
}

The output file has the filename scanned_file.json. The next script can read the JSON and process the files or analyze the content of the scanned directories.

File and Directory Handlers

The walker4folder has a default file handler and a default directory handler, that pushes the found files and folders to the JSON. The predefined file handler and folder holder is implemented directly

const w4f = require('walker4folder');

let scan_json = {
    "dirs": [],
    "files": []
}

function handle_dir(file,pathFile,dirAppend,options) {
  // e.g. dirAppend="libs" and file="js"
  scan_json.dirs.push(dirAppend+file);
  // pushes the relative path "libs/js" to array 'dirs'
  // complete path is available in pathFile="./src/libs/js"
}

function handle_file(file,pathFile,dirAppend,options) {
  // e.g. dirAppend="libs/js/" and file="mylib.js"
  scan_json.files.push(dirAppend+file);
  // pushes relative path "libs/js/mylib.js" to array 'files'
  //the full path is available with pathFile="./src/libs/js/mylib.js"
}

// start scan at directory "./src" and
// call the walker4folder with file and directory handlers
w4f.walker4folder("./src",handle_file,handle_dir);
w4f.save_scanned();

Select Files according to Extensions

The following application of walker4folder explains the selection of a specific files that allows to perform a specific search-and-replace task for all selected files. We explain the application by a specific use-case:

• Search all html files in the folder www/ and all subdirectories.
• load those html files and perform the search-and-replace tasks for each html file
• save the file back to the file system.

At first we filter all files with the file handler.

const w4f = require('walker4folder');

function my_handle_file(file,pathFile,dirAppend,options) {

  var ext = w4f.get_extension(pathFile);
  if (ext == "html") {
    console.log("Found File:  '" + pathFile + "' with extension '" + ext + "'");
  }
}

w4f.walker4folder("./www",my_handle_file);

The console.log() generates the following messages for each found file. It may look like this:

Found File: 'www/index.html' with extension 'html'
Found File: 'www/other/myfile1.html' with extension 'html'
Found File: 'www/other/myfile2.html' with extension 'html'

Search and Replace in all Selected Files

In the last script above html files are filtered from all found files Now we replace the console.log by

• load_file(),
• search_replace() and
• save_file() operation. The script could look like this. The following task of the script is to replace the import of Javascript library

const w4f = require('walker4folder');

function replace_in_file(file,pathFile,dirAppend,options) {

  var ext = w4f.get_extension(pathFile);
  // Select HTML files only with extension "html" e.g. "index.html"
  if (ext == "html") {
    console.log("Found File:  '" + pathFile + "' with extension '" + ext + "'");
    // load file
    var vContent = w4f.load_file(pathFile);
    // replace the library name "lib-v0.7.1.min.js" by "lib-v1.0.4.js" in HTML
    vContent = vContent.replace("lib-v0.7.1.min.js","lib-v1.0.4.js");
    // save the modified file will the updated content to e.g. "index.html.out".
    w4f.save_file(pathFile+".out",vContent);
    // remove ".out" if you want to save in the same file.
  }
}

w4f.walker4folder("./www",replace_in_file);

Ignore Files and Folders

You can ignore specific files and folders with the options.

let options = {
  "files": {
    "ignore": [".DS_Store",".gitignore"]
  },
  "dirs": {
    "ignore": ["node_modules",".git"]
  }
};

The files and folders that are mentioned in the ignore array will not be scanned. If you want to filter in a more advanced way use the file handler or the directory handlers and apply regular expressions on file, path or extension of files. In the example above two files .DS_Store and .gitignore

Recursion Depth - Directories

You might want to search in the current directory only or just in the start directory e.g. src/. This is the recursion depth 0. If you want to scan files in the start directory (e.g. src/) in the subdirectories one level deeper (e.g. src/md/ and src/html) but not the subdirectories 2 levels deeper (e.g. src/md/input/ and src/html/output/) then your recursion depths is 1.

The function get_recursion_depth(pPath) returns the recursion depth of the relative path from the start directory.

The following script shows how you can check the current of file or directory depending on the returned recursion depth you can decide want to do depending on the returned recursion depth of the file or folder.

const w4f = require('walker4folder');

function my_handle_file(file,pathFile,relativePath,options) {

  var rd = w4f.get_recursion_depth(relativePath);
  if (rd <= 2) {
    console.log("Found File:  '" + pathFile + "' with recursion depth " + rd + "." );
  }
}

w4f.walker4folder("./www",my_handle_file);

Scanned a specific directory

This call of the function walker4folder runs over a specific directory ./src with directory name as first parameter.

const w4f = require('walker4folder');
w4f.walker4folder("./src");
w4f.save_scanned();

The function save_scanned() stores again the scanned folders and files into a JSON for further processing. The output file has again the filename scanned_file.json.

If you provide an argument for w4f.save_scanned() you can define the filename for the JSON the scanned files are stored.

const w4f = require('walker4folder');
w4f.walker4folder("./src");
w4f.save_scanned("./found_files.json");

Scanned a specific directory with Callback function

If you want to handle files, or filter files then you can provide a specific callback functions for files and folders. The following callback function do nothing special. They just provide the output of the paramters.

const w4f = require('walker4folder');

function my_handle_file(file,pathFile,dirAppend,options) {
  console.log("File:         '" + file + "'");
  console.log("Path File:    '" + pathFile + "'");
  console.log("Subdirectory: '" + dirAppend + "'");
}

function my_handle_dir(file,pathDir,dirAppend,options) {
  console.log("Directory:           '" + file + "'");
  console.log("Path Dir:            '" + pathDir + "'");
  console.log("Parent Subdirectory: '" + dirAppend + "'");
}

w4f.walker4folder("../src",my_handle_file);
w4f.walker4folder("../src",my_handle_file,my_handle_dir);
w4f.walker4folder("../src",null,my_handle_dir);

• The first call w4f.walker4folder("../src/",my_handle_file) of the walker4folder replaces just the file handler with you own handler my_handle_file.
• The second call w4f.walker4folder("../src/",my_handle_file,my_handle_dir) of the walker4folder replaces both the file handler and the directory handler with you own file handler my_handle_file and directory handler my_handle_dir.
• The third call w4f.walker4folder("../src/",my_handle_file); of the walker4folder replaces just the directory handler with you own handler my_handle_dir. The second parameter for the file handler is null, so the default file handler is used that pushes the found files to the JSON that can be saved with w4f.save_scanned().

Options of walker4folder

The 4th parameter of w4f.walker2folder() call contains options. If you do not use the file handlers or directory handlers provide null as argument.

Console Log for all visited files and directories

The option options.logfiles is a boolean variable that defines if the folder visitor walker4folder reports all visited files to the console i.e. a command console.log() is called that reports that a specific file was found by the folder visitor. That does not mean that the file is processed or modified by the file handler e.g. my_handle_file(). The options are also passed to the file handler as 4th parameter so you can use the options also for your file handler.

const w4f = require('walker4folder');

function my_handle_file(file,pathFile,dirAppend,options) {
  console.log("File:         '" + file + "'");
  console.log("Path File:    '" + pathFile + "'");
  console.log("Subdirectory: '" + dirAppend + "'");
}

let options = {
  "logfiles": true,
  "logdirs":  false
};
w4f.walker4folder("../src",my_handle_file);
w4f.walker4folder("../src",my_handle_file,my_handle_dir);
w4f.walker4folder("../src",null,my_handle_dir);

Furthermore options.logdirs is a boolean variable that defines if the folder visitor walker4folder reports all visited folders to the console i.e. with the command console.log(). The options are also passed to the directory handler e.g. my_handle_dir() as 4th parameter and therefore you can use the options defining specific tasks the directory handler should perform depending on the settings in the options.

const w4f = require('walker4folder');

function my_handle_dir(file,pathDir,dirAppend,options) {
  console.log("Comment: "+options.comment);
  console.log("Directory:           '" + file + "'");
  console.log("Path Dir:            '" + pathDir + "'");
  console.log("Parent Subdirectory: '" + dirAppend + "'");
}

var options = {
  "logdirs":  true,
  "comment": "found directory";
};

w4f.walker4folder("../src",null,my_handle_dir,options);

API of Walker4Folder

Filename for JSON w4f.filename

The attribute w4f.filename contains the filename, which is used to save the scanned files and folders as a JSON. Default filename is w4f.filename = "scanned_file.json"

Function w4f.walker4folder()

The function w4f.walker4folder() starts the scan process of the directory. See tutorial above to start w4f.walker4folder() with specific parameters.

Function w4f.save_scanned()

If w4f.walker4folder() is started without file and directory handlers is uses the default file and directory handlers that populated a JSON with the files and folders that are found durch the walk through the folders and its subdirectory. w4f.save_scanned() saves the JSON into the file with the filename w4f.filename = "scanned_file.json". With w4f.walker4folder("myfiles.json") you can define the output filename for the JSON.

Function w4f.()

The function `` "load_file": ls.load_file,

Function w4f.load_file()

The function load_file(pFileName) loads a text or string from a specific the file with name pFileName. File types can be any text files e.g. with the extension:

• html
• xml
• js
• txt
• svg
• .... Remark: Do not perform the load_file() on binary files.

Function w4f.save_file()

The function save_file(pFileName,pContent) saves a text file with the string variable pContent into the file with name pFileName.

var vContent = "My name is Bond, James Bond";
w4f.save_file("person.json",vContent);

Remark: Do not perform the save_file() on binary files.

Function w4f.load_json()

The function load_json(pFileName) loads a JSON from a specific the file with name pFileName.

var vJSON  = w4f.load_json("person.json");
// e.g.
// vJSON = {
//  "firstname": "James",
//   "lastname": "Bond",
//   "age":45
// }

Function w4f.save_json()

The function save_json(pFileName,pJSON) saves a JSON pJSON into the file with name pFileName.

var vJSON = {
  "firstname": "James",
  "lastname": "Bond",
  "age":45
}

w4f.save_json("person.json",vJSON);

Function w4f.remove_extension()

The function remove_extension(pPath) removes the extension from a file path. That is useful if the scan of folders reads files and creates a new file for the found extension.

var name = w4f.remove_extension("/home/user/documents/readme.html");
// "name" contains filename without extension "/home/user/documents/readme"

Function w4f.is_string()

The function is_string(pVar) checks if a provided variable pVar is a string.

var bool1 = w4f.is_string("/home/user/documents/readme.html");
// vbool1 = true
var bool2 = w4f.is_string(67873);
// vbool2 = false

Function w4f.get_extension()

The function w4f.get_extension() extracts the extension for a provided URL of path for the file.

var name = w4f.get_extension("/home/user/documents/readme.html");
// name="html"

Function w4f.get_name4url()

The function get_name4url() extracts the name without the extension for a provided URL of path to a filename.

var name = w4f.get_name4url("/home/user/documents/readme.html");
// name="readme"

Function w4f.get_nameext4url()

The function get_nameext4url() extracts the name and extension for a provided URL of path to a filename.

var name = w4f.get_nameext4url("/home/user/documents/readme.html");
// name="readme.html"