Adobe Illustrator script to select highlighted layers. Written by @Qwertyfly and only slightly modified by me. Original code and discussion can found here: https://forums.adobe.com/message/8328893

SelectActiveLayers.jsx

#target illustrator

function make() {
	
	var name = 'temp'; // Action name.
	var set = 'temp'; // Set name.
	var level = app.userInteractionLevel;
	var action;
	
	app.userInteractionLevel = UserInteractionLevel.DONTDISPLAYALERTS;
	
	action = [
		'/version 3',
		'/name [',
			'4', // Group name character count.
			'74656d70', // Group name as a hash.
		']',
		'/isOpen 0',
		'/actionCount 1',
		'/action-1 {',
			'/name [',
				'4', // Action name character count.
				'74656d70', // Action name as a hash.
			']',
			'/keyIndex 0',
			'/colorIndex 0',
			'/isOpen 0',
			'/eventCount 1',
			'/event-1 {',
				'/useRulersIn1stQuadrant 0',
				'/internalName (ai_plugin_Layer)',
				'/localizedName [',
					'5',
					'4c61796572',
				']',
				'/isOpen 0',
				'/isOn 1',
				'/hasDialog 0',
				'/parameterCount 3',
				'/parameter-1 {',
					'/key 1836411236',
					'/showInPalette -1',
					'/type (integer)',
					'/value 7',
				'}',
				'/parameter-2 {',
					'/key 1937008996',
					'/showInPalette -1',
					'/type (integer)',
					'/value 23',
				'}',
				'/parameter-3 {',
					'/key 1851878757',
					'/showInPalette -1',
					'/type (ustring)',
					'/value [',
						'11',
						'48696465204f7468657273',
					']',
				'}',
			'}',
		'}'
	].join('\n');
	
	create(action);
	
	app.doScript(name, set, false);
	action = null;
	app.unloadAction(set, '');
	app.userInteractionLevel = level;
	
}

function create(str) {
	
	var aia = new File('~/temp.aia');
	
	aia.open('w');
	aia.write(str);
	aia.close();
	
	app.loadAction(aia);
	
	aia.remove();
	
}

function get() {
	
	var doc = app.activeDocument;
	var layers = doc.layers;
	var cached = [];
	var selected = [];
	var i;
	
	// Record existing visibility:
	for (i = 0; i < layers.length; i++) {
		
		cached.push(layers[i].visible);
		
		if ( ! layers[i].visible) {
			
			layers[i].visible = true;
			
		}
		
	}
	
	// Make all selected layers visible and hide the rest:
	make();
	
	// Grab the selected visible layers:
	for (i = 0; i < layers.length; i++) {
		
		if (layers[i].visible) {
			
			selected.push(layers[i]);
			
		}
		
	}
	
	// Restore visibility:
	for (i = 0; i < layers.length; i++) {
		
		layers[i].visible = cached[i];
		
	}
	
	// Return the selected layers array:
	return selected;
	
}

var mylayers = get();
for (var i = 0; i < mylayers.length; i++) {
	
	alert(mylayers[i].name + ", " + mylayers[i].visible);
	
}

temp.aia

/version 3
/name [
	4
	74656d70
]
/isOpen 0
/actionCount 1
/action-1 {
	/name [
		4
		74656d70
	]
	/keyIndex 0
	/colorIndex 0
	/isOpen 0
	/eventCount 1
	/event-1 {
		/useRulersIn1stQuadrant 0
		/internalName (ai_plugin_Layer)
		/localizedName [
			5
			4c61796572
		]
		/isOpen 0
		/isOn 1
		/hasDialog 0
		/parameterCount 3
		/parameter-1 {
			/key 1836411236
			/showInPalette -1
			/type (integer)
			/value 7
		}
		/parameter-2 {
			/key 1937008996
			/showInPalette -1
			/type (integer)
			/value 23
		}
		/parameter-3 {
			/key 1851878757
			/showInPalette -1
			/type (ustring)
			/value [
				11
				48696465204f7468657273
			]
		}
	}
}

Original code and discussion can found here:

• Select only highlighted layers?