../ does work, but path resolution happens where the HTML file is, not where the js file is. This is because the HTML file is the page executing the Javascript. You can see this by looking at the URL for the request that returned a 403: https://v6p9d9t4.ssl.hwcdn.net/html/assets/texts/imgs/background.txt The URL does not include your project's id after the /html/ path, so its' going up one more directory than you expect. Hope that helps.