var iframe = document.getElementById('youriframe');
iframe.src = iframe.src;

document.getElementById('FrameID').contentWindow.location.reload(true);

document.getElementById('YOUR IFRAME').contentDocument.location.reload(true);

var f = document.getElementById('iframe1');
f.src = f.src;

<td><iframe name="idFrame" id="idFrame" src="chat.txt" width="468" height="300"></iframe></td>

window.onload = function(){
setInterval(function(){
    parent.frames['idFrame'].location.href = "chat.txt";
},1000);}

var iframes = document.getElementsByTagName('iframe');
var yourIframe = null
for(var i=0; i < iframes.length ;i++){
    var source =  iframes[i].attributes.src.nodeValue;
    if(source.indexOf('/yourSorce') > -1){
        yourIframe = iframes[i];
    }
}
var iSource = yourIframe.attributes.src.nodeValue;
yourIframe.src = iSource;

window.addEventListener('change', function(e) {
  if (e.data === 'Please reload yourself') {
    var skipCache = true; // true === Shift+F5
    window.location.reload(skipCache);
  }
}

var iframe = document.getElementById('my-iframe');
var targetOrigin = iframe.src; // Use '*' if you don't care
iframe.postMessage('Please reload yourself', targetOrigin);

function reloadFrame(iFrame) {

    iFrame.parentNode.replaceChild(iFrame.cloneNode(), iFrame);

}

iframe.src = iframe.src;

iframe.src =  iframe.src.split("?")[0] + "?_=" + new Date().getTime();

var wasSrc = iframe.src

iframe.onload = function() {
    iframe.onload = undefined;
    iframe.src = wasSrc;
}

iframe.contentWindow.location.reload();

function refreshFrame(){
    $('#myFrame').attr('src', "http://blablab.com?v=");
}

`<iframe id="myFrame" src=""></iframe>`