JSFiddle - React, Tailwind, and code Playground

HTML

<div id="thing">
</div>
<div id="otherThing">
    <div id="sibling">
    </div>
    <div id="target9999">
    </div>
    <div id="nextSibling">
        <div id="target999">
            <div id="target93">
            </div>
        </div>
    </div>
</div>

JavaScript

document.findElementWithIdLike = function(prefix) {
    return findChildWithIdLike(document.body, prefix);
};

document.findElementsWithIdLike = function(prefix) {
    var results = [];
    findChildrenWithIdLike(document.body, prefix, results);
    
    return results;
};

window.findChildWithIdLike = function(node, prefix) {
    if (node && node.id && node.id.indexOf(prefix) == 0) {
        //match found
        return node;
    }
    
    //no match, check child nodes
    for (var index = 0; index < node.childNodes.length; index++) {
        var child = node.childNodes[index];
        var childResult = findChildWithIdLike(child, prefix);
        if (childResult) {
            return childResult;
        }
    }
};

window.findChildrenWithIdLike = function(node, prefix, results) {
    if (node && node.id && node.id.indexOf(prefix) == 0) {
        //match found
        results.push(node);
    }
    
    //check child nodes
    for (var index = 0; index < node.childNodes.length; index++) {
        var child = node.childNodes[index];
        var childResult = findChildrenWithIdLike(child, prefix, results);
        if (childResult) {
            results.push(childResult);
        }
    }
};

alert(document.findElementsWithIdLike("target").length);