Chars allowed between src and = in img tag

5

5

5

<script>
window.onerror = () => true; 
</script>

<img src$[chr]=data:text/plain, id="testImg">

const img = document.getElementById('testImg');
if (img.hasAttribute('src') && img.getAttribute('src') === 'data:text/plain,') {
    log($[i]);
}