How to get POSIX path of the current script's

Question

In AppleScript it’s possible to get the the POSIX path of the folder the current script is located in using this line:

POSIX path of ((path to me as text) & "::")

Example result: /Users/aaron/Git/test/

What’s the JavaScript equivalent?

Answer 1

To complement the helpful existing answers by providing self-contained utility functions:

// Return the POSIX path of the folder hosting this script / app.
// E.g., from within '/foo/bar.scpt', returns '/foo'.
function myPath() {
    var app = Application.currentApplication(); app.includeStandardAdditions = true
    return $(app.pathTo(this).toString()).stringByDeletingLastPathComponent.js
}

// Return the filename root (filename w/o extension) of this script / app.
// E.g., from within '/foo/bar.scpt', returns 'bar'.
// (Remove `.stringByDeletingPathExtension` if you want to retain the extension.)
function myName() {
    var app = Application.currentApplication(); app.includeStandardAdditions = true
    return $(app.pathTo(this).toString()).lastPathComponent.stringByDeletingPathExtension.js
}

Note: These functions make use of the shortcut syntax forms for the ObjC bridge ($(...) for ObjC.wrap() and .js for ObjC.unwrap(), and also take advantage of the fact that the Foundation framework's symbols are available by default - see the OS X 10.10 JXA release notes.

---

It's easy to generalize these functions to provide the equivalents of the POSIX dirname and basename utilities:

// Returns the parent path of the specified filesystem path.
// A trailing '/' in the input path is ignored.
// Equivalent of the POSIX dirname utility.
// Examples:
//    dirname('/foo/bar') // -> '/foo'
//    dirname('/foo/bar/') // ditto
function dirname(path) {
  return $(path.toString()).stringByDeletingLastPathComponent.js
}

// Returns the filename component of the specified filesystem path.
// A trailing '/' in the input path is ignored.
// If the optional <extToStrip> is specified:
//   - If it it is a string, it is removed from the result, if it matches at
//     the end (case-sensitively) - do include the '.'
//   - Otherwise (Boolean or number), any truthy value causes any extension
//     (suffix) present to be removed.
// Equivalent of the POSIX basename utility; the truthy semantics of the
// 2nd argument are an extension.
// Examples:
//    basename('/foo/bar') // -> 'bar'
//    basename('/foo/bar/') // ditto
//    basename('/foo/bar.scpt', 1) // -> 'bar'
//    basename('/foo/bar.scpt', '.scpt') // -> 'bar'
//    basename('/foo/bar.jxa', '.scpt') // -> 'bar.jxa'
function basename(path, extToStrip) {
  path = path.toString()
  if (path[path.length-1] === '/') { path = path.slice(0, -1) }
  if (typeof extToStrip === 'string') {
    return path.slice(-extToStrip.length) === extToStrip ? $(path).lastPathComponent.js.slice(0, -extToStrip.length) : $(path).lastPathComponent.js    
  } else { // assumed to be numeric: if truthy, strip any extension
    return extToStrip ? $(path).lastPathComponent.stringByDeletingPathExtension.js : $(path).lastPathComponent.js    
  }
}