Regex to extract all image URLs from HTML string not correct

Do not use regex for this. Use the DOMParser API and its parseFromString() method.

let str = "<img src='https://www.example.com'>";

let DOMParsing = new DOMParser()
let parsed = DOMParsing.parseFromString(str, "text/html")

// Now you can use querySelector to target the wanted element
// or querySelectorAll and a loop for multiple elements
let imgURL = parsed.querySelector("img").src

console.log(imgURL)