SOURCE

var div1 = document.getElementById('div1');
var div2 = document.getElementById('div2');
var div3 = document.getElementById('div3');
var div4 = document.getElementById('div4');

function button1Handler(){
  // $("#div1").html($("#div2").html())
  div1.innerHTML = div2.innerHTML
}

function button2Handler(){
// $("#div3").html($("#div4").html())
    div3.innerHTML = div4.innerHTML

}

<div id="div1">div1</div>
<div id="div2">2333</div>
<button onclick="button1Handler()">button1</button>

<div id="div3">div3</div>
<div id="div4"><span style="color:red">div4</span></div>

<button onclick="button2Handler()">button2</button>