An Adobe Illustrator script for resizing the first artboard of a document horizontally, to fit the width of the first item on the artboard, but leaving the artboard height the same

ResizeArtboard.jsx

#target illustrator
#targetengine main

var doc = app.activeDocument;
var artboard = doc.artboards[0];
var art = doc.pageItems[0];
var coordinates = art.position;
var desiredW = art.width;

art.position = [ 0, coordinates[1] ];
artboard.artboardRect = [
  artboard.artboardRect[0],
  artboard.artboardRect[1],
  desiredW,
  artboard.artboardRect[3]
];