First send a request to a page, get the content and parse it to html. Then get all img tags by using getElementsByTagName method.

For example, if you want to get all img tags on https://jsonplaceholder.typicode.com, your code should be like below.

fetch('https://jsonplaceholder.typicode.com').then(function (response) {
    // The API call was successful!
    return response.text();
}).then(function (html) {

    // Convert the HTML string into a document object
    var parser = new DOMParser();
    var doc = parser.parseFromString(html, 'text/html');
    var imgTags = doc.getElementsByTagName("img");
    console.log(imgTags);
    
    var imgTagArr = [...imgTags];
    imgTagArr.forEach(img => console.log(img.src)); //iterate the all img tag srcs
}).catch(function (err) {
    // There was an error
    console.warn('Something went wrong.', err);
});

Example output:

Yup , in Html like <img class="pqr" url ="xxxxxxx-yyy"/>
in Js file:

const img =document.querySelector('.pqr')
img.src // <-- this will give the src of the image