JSFiddle - React, Tailwind, and code Playground

HTML

<textarea id="userinput" cols="50" rows="10">
<img src="dummy" onerror="alert('owned');" onload="alert('still owned');" />
</textarea>
<br />
<button id="button">Inspect user input without inserting into DOM</button>

JavaScript

var userinput = document.getElementById("userinput"),
	button = document.getElementById("button");

button.addEventListener("click", function () {
	var content = userinput.value,
        div = document.createElement("div");
    
    console.log(content);
    
    div.innerHTML = content; // browser will try fetching the resource specified in src attribute.
    
    var imgs = div.getElementsByTagName("img");
    
    for (var i = 0; i < imgs.length; i += 1) {
    	//delete imgs[i].src; // Even deleting the src attribute comes too late.
        imgs[i].src = "http://jsfiddle.net/img/logo.png"; // browser will try fetching the resource at this new URL.
    }
    
    // div was never inserted into DOM!
});