Convert ID to class name not working || so that I can use it multiple time

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I have a code pen code. I need to convert the output

var preview = document.getElementById("preview");

to class rather than ID. Can anyone help? Thanks in advance

Codepen Link Here

"use strict";
function dragNdrop(event) {
    var fileName = URL.createObjectURL(event.target.files[0]);
    var preview = document.getElementById("preview");
    var previewImg = document.createElement("img");
    previewImg.setAttribute("src", fileName);
    preview.innerHTML = "";
    preview.appendChild(previewImg);
}
function drag() {
    document.getElementById('uploadFile').parentNode.className = 'draging dragBox';
}
function drop() {
    document.getElementById('uploadFile').parentNode.className = 'dragBox';
}

What I have tried:

<pre>"use strict";
function dragNdrop(event) {
    var fileName = URL.createObjectURL(event.target.files[0]);
    var preview = document.getElementsByClassName("preview");
    var previewImg = document.createElement("img");
    previewImg.setAttribute("src", fileName);
    preview.innerHTML = "";
    preview.appendChild(previewImg);
}
function drag() {
    document.getElementById('uploadFile').parentNode.className = 'draging dragBox';
}
function drop() {
    document.getElementById('uploadFile').parentNode.className = 'dragBox';
}

Posted 18-Mar-21 7:47am

Subir Banik

Updated 18-Mar-21 23:00pm

v2

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Richard Deeming · Answer 1 · 2021-03-18T23:00:00

Solution 1

The clue is in the method name - getElementsByClassName returns multiple elements.

Either take the first element:

JavaScript

var preview = document.getElementsByClassName("preview")[0];

or use querySelector:

JavaScript

var preview = document.querySelector(".preview");

Document.querySelector() - Web APIs | MDN[^]

Posted 18-Mar-21 23:00pm

Richard Deeming

Comments

Subir Banik 19-Mar-21 10:08am

Thanks. I did what you said but the issue is it is only showing a single preview. I need to show the preview of the image two times. Can you please help?