Set keyboard caret position in html textbox

Excerpted from Josh Stodola's Setting keyboard caret Position in a Textbox or TextArea with Javascript

A generic function that will allow you to insert the caret at any position of a textbox or textarea that you wish:

function setCaretPosition(elemId, caretPos) {
    var elem = document.getElementById(elemId);

    if(elem != null) {
        if(elem.createTextRange) {
            var range = elem.createTextRange();
            range.move('character', caretPos);
            range.select();
        }
        else {
            if(elem.selectionStart) {
                elem.focus();
                elem.setSelectionRange(caretPos, caretPos);
            }
            else
                elem.focus();
        }
    }
}

The first expected parameter is the ID of the element you wish to insert the keyboard caret on. If the element is unable to be found, nothing will happen (obviously). The second parameter is the caret positon index. Zero will put the keyboard caret at the beginning. If you pass a number larger than the number of characters in the elements value, it will put the keyboard caret at the end.

Tested on IE6 and up, Firefox 2, Opera 8, Netscape 9, SeaMonkey, and Safari. Unfortunately on Safari it does not work in combination with the onfocus event).

An example of using the above function to force the keyboard caret to jump to the end of all textareas on the page when they receive focus:

function addLoadEvent(func) {
    if(typeof window.onload != 'function') {
        window.onload = func;
    }
    else {
        if(func) {
            var oldLoad = window.onload;

            window.onload = function() {
                if(oldLoad)
                        oldLoad();

                func();
            }
        }
    }
}

// The setCaretPosition function belongs right here!

function setTextAreasOnFocus() {
/***
 * This function will force the keyboard caret to be positioned
 * at the end of all textareas when they receive focus.
 */
    var textAreas = document.getElementsByTagName('textarea');

    for(var i = 0; i < textAreas.length; i++) {
        textAreas[i].onfocus = function() {
            setCaretPosition(this.id, this.value.length);
        }
    }

    textAreas = null;
}

addLoadEvent(setTextAreasOnFocus);

I found an easy way to fix this issue, tested in IE and Chrome:

function setCaret(elemId, caret)
 {
   var elem = document.getElementById(elemId);
   elem.setSelectionRange(caret, caret);
 }

Pass text box id and caret position to this function.

I would fix the conditions like below:

function setCaretPosition(elemId, caretPos)
{
 var elem = document.getElementById(elemId);
 if (elem)
 {
  if (typeof elem.createTextRange != 'undefined')
  {
   var range = elem.createTextRange();
   range.move('character', caretPos);
   range.select();
  }
  else
  {
   if (typeof elem.selectionStart != 'undefined')
    elem.selectionStart = caretPos;
   elem.focus();
  }
 }
}

HTMLInputElement.setSelectionRange( selectionStart, selectionEnd );

// References
var e = document.getElementById( "helloworldinput" );

// Move caret to beginning on focus
e.addEventListener( "focus", function( event )
{
    // References
    var e = event.target;

    // Action
    e.setSelectionRange( 0, 0 );            // Doesn’t work for focus event
    
    window.setTimeout( function()
    {
        e.setSelectionRange( 0, 0 );        // Works
        //e.setSelectionRange( 1, 1 );      // Move caret to second position
        //e.setSelectionRange( 1, 2 );      // Select second character

    }, 0 );

}, false );

Browser compatibility (only for types: text, search, url, tel and password): https://developer.mozilla.org/en-US/docs/Web/API/HTMLInputElement/setSelectionRange#Specifications