document.getElementById("ThingToSetFocusOn").focus();

window.onload=function(){

 document.getElementById("id_here").focus();

}

// id_here = put the id of the HTML element where you want to set focus.

focusMethod = function getFocus() {

  document.getElementById("myTextField").focus();

}

const input = document.querySelector('#first_name') as HTMLElement | null;

​

if (input != null) {

  input.focus();

}

<!-- In order to do it, you need to assign a tabindex... -->

<div tabindex="0">Hello World</div>