JSFiddle - React, Tailwind, and code Playground

HTML

<input type="text" value="ammmmmmm4545646344r6sf46sdfRob W" id="inputElement" />

JavaScript

/* @name caretAtEnd
 * @description Places caret at the end
 * @param elem  DOM element
 * @param focus boolean, optional. If true, the element will be focused.
 */
function caretAtEnd(elem, focus){
    var value = elem.value;

    //Add an extra character to the input field (necessary for this method)
    // An additional advantage is that the caret automatically moves to the end
    elem.value = elem.value + ".";

    try {
        // Create and simulate/trigger a [Backspace] keypress event.
        var evt = document.createEvent("KeyboardEvent");
        evt.initKeyEvent("keypress", 1, 1, null, 0, 0, 0, 0, 8, 0);
        elem.dispatchEvent(evt);
    } catch(e){
        //The current key event is not supported yet. Change back the value
        // In some browsers, the caret is at the end after executing this code.
        elem.value = value;
    }

    //Optionally, Focus on the element
    if(focus) elem.focus();
}
var element = document.getElementById("inputElement"); //Important: Get the DOM element!
caretAtEnd(element, true);