Writing JSON-style info to a file

exportSlicesJson.js

try { (function() {
	if (!fw.selection || !fw.selection.length) {
		return;
	}
	
	var json, filePath, file;
	json = '{"sprites":[';

	for(i=0;i < fw.selection.length;i++){
		var element = fw.selection[i];
		json += '{"key":"' + element.baseName + '","bounds":{"x":' + element.left + ',"y":' + element.top + ',"width":' + element.width + ',"height":' + element.height + '}},';
		
	};

	json = json.slice(0, json.length-1);
	json += ']}';

	filePath = fw.browseForFileURL("save");
	if (!filePath) {
		return;
	}
	
	Files.deleteFileIfExisting(filePath);
	Files.createFile(filePath, "TEXT", "????");

	file = Files.open(filePath, true);
	file.write(json);
	file.close();
})(); } catch (exception) {
	if (exception.lineNumber) {
		alert([exception, exception.lineNumber, exception.fileName].join("\n"));
	} else {
		throw exception;
	}
}

Sample result has null "name" values.

{"sprites":[{"key":null,"bounds":{"x":42,"y":0,"width":50,"height":34}},{"key":null,"bounds":{"x":0,"y":0,"width":42,"height":34}}]}

fixed name by changing it to baseName