const htmlString = `<img src="https://example.com/img1.png" alt="Image 1">
    <p>Some text</p>
    <img data-id="123" src='/images/relative/path.jpg'>
    <img src="http://cdn.example.net/assets/pic.gif">
    <img src="https://othersite.com/svgs/icon.svg?v=1.0'>`;

const imageUrls = [];
// Regex to find src attribute with a URL starting with http/https
const imgUrlRegex = /<img[^>]+src=["'](https?://[^"'\s]+)["']/gi;

let match;
while ((match = imgUrlRegex.exec(htmlString)) !== null) {
    imageUrls.push(match[1]);
}

console.log(imageUrls);
// Expected output:
// [
//   "https://example.com/img1.png",
//   "http://cdn.example.net/assets/pic.gif",
//   "https://othersite.com/svgs/icon.svg?v=1.0"
// ]