@bmacnaughton/action-walk

action-walk

Minimal utility to walk directory trees performing actions on each directory entry. action-walk has no external production dependencies and has only one strong opinion - don't presume anything about why the directory tree is being walked.

No presumptions means that this does little more than walk the tree. There are two options to facilitate implementing your code on top of action-walk. If the boolean option stat is truthy action-walk will execute fs.stat on the entry and pass that to you action handler. If the option own is present action-walk will pass that to the action functions in a context object.

usage

action-walk should run on any version of node that supports the node: prefix when requiring built-in modules. It is tested on even-numbered versions of node starting with 14 on both Linux and Windows.

npm install action-walk

examples

//
// example to walk the directory tree, skipping node_modules, and
// totaling the number of bytes in each file.
//
const walk = require('@bmacnaughton/action-walk');

function dirAction (path, context) {
  const {dirent, stat, own} = context;
  if (own.skipDirs && own.skipDirs.indexOf(dirent.name) >= 0) {
    return 'skip';
  }
  own.total += stat.size;
}
function fileAction (path, context) {
  const {stat, own} = context;
  own.total += stat.size;
}

const own = {total: 0, skipDirs: ['node_modules']};
const options = {
  dirAction,
  fileAction,
  own,
  stat: true
};

walk('.', options)
  .then(() => {
    console.log('total bytes in "."', own.total);
  });

// executed in the action-walk package root it will print something like
// total bytes in "." 14778

see test/basics.test.js or bin/walk.js for other examples.

api

await walk(directory, options = {})

options

• dirAction - called for each directory. If it returns 'skip', action-walk will not recurse into the directory.
• fileAction - called for each file and, if options.linkAction is not set, each symbolic link.
• linkAction - called for each symbolic link when options.linkAction is set.
• otherAction - called when the entry is not a file, directory, or symbolic link.
• stat - if 'lstat' call fs.lstat on the entry and add it to the action context as the stat property. if otherwise truthy use fs.stat.
• own - add this to the action context. it is your context for the action functions.

It's possible to call walk() with no options but probably not useful unless all you're wanting to do is seed the disk cache with directory entries. The action functions are where task-specific work is done.

Each of the action function (dirAction, fileAction, linkAction, otherAction) is called with two arguments:

• filepath for the entry starting with directory, e.g., if directory is test and the entry is basics.test.js then filepath will be test/basics.test.js.
• context is an object:

{
  dirent, // the fs.Dirent object for the directory entry
  stat,   // if `options.stat`, the object returned by `fs.stat` or `fs.lstat`
  stack,  // the stack of directories above the current dirent item.
  own     // `options.own`, if provided.
}

dirAction is the only function with return value that matters. If dirAction returns the string 'skip' (either directly or via a Promise) then walk() will not walk that branch of the directory tree.

All the action functions can return a promise if they need to perform asynchronous work but only the value of dirAction is meaningful.

todo

• add error handling