printSwatches.js

// let's get a hold on the Sketch API
const sketch = require('sketch');
//let's expose these globally
var document = sketch.fromNative(context.document);
var page = document.selectedPage;
var Rectangle = require('sketch/dom').Rectangle;
var Shape = require('sketch/dom').Shape;
var Style = require('sketch/dom').Style;
var Group = require('sketch/dom').Group;

var selectedArtboard;

if(context.selection.length === 1 ){
  const layer = context.selection.firstObject();
if( layer && layer.isKindOfClass(MSArtboardGroup) ){
    selectedArtboard = layer;
    generateSwatch(context);
  }
} else {
    console.log('Export failed, please select one artboard');
}

// swatches = document.sharedLayerStyles;
// swatches.sort(dynamicSort("name"));

function dynamicSort(property) {
    var sortOrder = 1;
    if(property[0] === "-") {
        sortOrder = -1;
        property = property.substr(1);
    }
    return function (a,b) {
        var result = (a[property] < b[property]) ? -1 : (a[property] > b[property]) ? 1 : 0;
        return result * sortOrder;
    }
}

function generateSwatch(context) {

  var offset = 66;
  var x = 0;
  var y = 0;

for (i=0;i<=document.sharedLayerStyles.length;i++) {
      
      const rectangle = new Shape({
        name: "rectangle",
        parent: selectedArtboard,
        frame: new Rectangle(x, y, 84, 38),
        style: {
          fills: [{enabled:true}],
          borders: [{enabled:true}]
        },
        sharedStyleId: document.sharedLayerStyles[i].id
      })

      rectangle.style.syncWithSharedStyle(document.sharedLayerStyles[i]);

      const text = new sketch.Text({
        parent: selectedArtboard,
        text: document.sharedLayerStyles[i].name,
        frame: new Rectangle(x, y+42),
        name: document.sharedLayerStyles[i].name
      });
      
      new Group();
    
      var group = new Group({
        name: 'Artboard_label',
        parent: selectedArtboard,
        locked: true
      })
      group.frame.width = rectangle.frame.width;
      group.frame.height = rectangle.frame.height;
      group.layers.push(rectangle);
      group.layers.push(text);
      
      y=y+offset;
  }
}