How can I write UTF-8 files using JavaScript for Mac Automation?

Question

In short - what is the JavaScript for Mac Automation equivalent of AppleScript\'s as «class utf8» ?

I have a unicode string that I\'m t

Answer 1

@PatrickWayne has the correct solution.

I already had this function in my lib, so I thought I'd share it. It uses the same key commands.

//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
function writeFile(pPathStr, pOutputStr) {  //  @File @Write @ObjC
  /*  VER: 2.0  2017-03-18  
---------------------------------------------------------------
  PARAMETERS:
    pPathStr    | string  | Path of file to write.  May use tilde (~)
    pOutputStr  |  string  |  String to be output to file.
  */
  
  //--- CONVERT TO NS STRING ---
  var nsStr       = $.NSString.alloc.initWithUTF8String(pOutputStr)
  
  //--- EXPAND TILDE AND CONVERT TO NS PATH ---
  var nsPath      = $(pPathStr).stringByStandardizingPath
  
  //--- WRITE TO FILE ---
  //      Returns true IF successful, ELSE false
  var successBool  = nsStr.writeToFileAtomicallyEncodingError(nsPath, false, $.NSUTF8StringEncoding, null)
  
  if (!successBool) {
    throw new Error("function writeFile ERROR:\nWrite to File FAILED for:\n" + pPathStr)
  }
  
  return successBool
  
};

Answer 2

JXA can't do symbol types (type and enumerator names) right, and it can't do raw four-char codes at all. Either stick to AppleScript, which is the only officially supported option that speaks Apple events right, or use the Cocoa bridge to write a NSString to file in NSUTF8StringEncoding, c.f. Patrick's solution.

Answer 3

While I was unable to find a way to do it with JavaScript only, I ended up utilizing the Objective-C Bridge to accomplish UTF-8 file write-out.

Here is the code that I used. This is JavaScript code that invokes the Objective-C NSString class, and it replaces the writeTextToFile function that I mentioned above altogether:

objCText = $.NSString.alloc.initWithUTF8String(text);
objCText.writeToFileAtomically(filePathString, true);

Answer 4

If you want to ensure your file gets written with UTF8 encoding, use NSString's writeToFile:atomically:encoding:error function, like so:

fileStr = $.NSString.alloc.initWithUTF8String( 'your string here' )
fileStr.writeToFileAtomicallyEncodingError( filePath, true, $.NSUTF8StringEncoding, $() )

You would think that writing an NSString object initialized from a UTF8 string would get written out as UTF8 but I've found from experience that writeToFile:atomically does not honor the encoding of the string being written out. writeToFile:atomically:encoding:error explicitly specifies which encoding to use. On top of that, writeToFile:atomically has been deprecated by Apple since OS X 10.4.