Is there any way to load css and javascript from a string?

Question

I've seen many examples of loading CSS and javascript dynamically from a file. Here's a good example. But is there a way to load CSS or javascript as a string? For example, something like:

var style = ".class { width:100% }"
document.loadStyle(style);

Or something of that nature.

Answer 1

var javascript = "alert('hello');";
eval(javascript);

This will load the JavaScript from a string, but be warned that this is highly insecure and not recommended. If a malicious process ever interfered with your string of JavaScript, it could result in security issues.

As far as CSS goes, you can append a style tag to the page using jQuery, like so:

$('head').append("<style>body { background-color: grey; }</style>");

Or, for the JavaScript purists:

var s = document.createElement("style");
s.innerHTML = "body { background-color:white !important; }";
document.getElementsByTagName("head")[0].appendChild(s);

Answer 2

Another way without using potentially dangerous eval and innerHTML is creating a link element with base64 encoded URL:

function loadCSS(cssStyles) {
  const link = document.createElement('link');
  link.href = `data:text/css;base64,${btoa(cssStyles)}`;
  link.type = 'text/css';
  link.rel = 'stylesheet';
  document.getElementsByTagName('head')[0].appendChild(link);
}