Получить все свойства окна, определенные пользователем?

Вам нужно будет делать эту работу самостоятельно. Прочтите все свойства в первый раз, когда сможете. С этого момента вы можете сравнивать список свойств со своим статическим.

var globalProps = [ ];

function readGlobalProps() {
    globalProps = Object.getOwnPropertyNames( window );
}

function findNewEntries() {
    var currentPropList = Object.getOwnPropertyNames( window );

    return currentPropList.filter( findDuplicate );

    function findDuplicate( propName ) {
        return globalProps.indexOf( propName ) === -1;
    }
}

Итак, теперь мы могли бы пойти как

// on init
readGlobalProps();  // store current properties on global object

и позже

window.foobar = 42;

findNewEntries(); // returns an array of new properties, in this case ['foobar']

Конечно, предостережение заключается в том, что вы можете «заморозить» глобальный список свойств только в то время, когда ваш скрипт может вызвать его в самый ранний момент.

Вы также можете сравнить окно с чистой версией окна вместо того, чтобы пытаться сделать снимок во время выполнения для сравнения. Я запустил это в консоли, но вы можете превратить его в функцию.

// make sure it doesn't count my own properties
(function () {
    var results, currentWindow,
    // create an iframe and append to body to load a clean window object
    iframe = document.createElement('iframe');
    iframe.style.display = 'none';
    document.body.appendChild(iframe);
    // get the current list of properties on window
    currentWindow = Object.getOwnPropertyNames(window);
    // filter the list against the properties that exist in the clean window
    results = currentWindow.filter(function(prop) {
        return !iframe.contentWindow.hasOwnProperty(prop);
    });
    // log an array of properties that are different
    console.log(results);
    document.body.removeChild(iframe);
}());

Это в том же духе, что и ответ @jungy, но мы можем сделать это в 3 строчки:

document.body.appendChild(document.createElement('div')).innerHTML='<iframe id="temoin" style="display:none"></iframe>';

for (a in window) if (!(a in window.frames[window.frames.length-1])) console.log(a, window[a])

document.body.removeChild($$('#temoin')[0].parentNode);

Сначала мы добавляем скрытый iframe; затем мы проверяем существующие переменные на соответствие стандартному JavaScript API в iframe; затем мы удаляем iframe.

Для удобства работы было бы полезно отсортировать результаты в алфавитном порядке, и это все еще возможно в версии из 3 строк:

document.body.appendChild(document.createElement('div')).innerHTML='<iframe id="temoin" style="display:none"></iframe>';

Object.keys(window).filter(a => !(a in window.frames[window.frames.length-1])).sort().forEach((a,i) => console.log(i, a, window[a]));

document.body.removeChild($$('#temoin')[0].parentNode);

И его можно запаковать в закладку:

javascript:document.body.appendChild(document.createElement('div')).innerHTML='<iframe%20id="temoin"%20style="display:none"></iframe>';Object.keys(window).filter(a=>!(a%20in%20window.frames[window.frames.length-1])).sort().forEach((a,i)=>console.log(i,a,window[a]));document.body.removeChild(document.querySelectorAll('#temoin')[0].parentNode);throw 'done';

Я запустил это в консоли в инструменте ChromeDev, и он скопировал все, что пользователь определил правильно

function getUserDefinedKeys() {
    const globalKeys = ["postMessage","blur","focus","close","parent","opener","top","length","frames","closed","location","self","window","document","name","customElements","history","locationbar","menubar","personalbar","scrollbars","statusbar","toolbar","status","frameElement","navigator","origin","external","screen","innerWidth","innerHeight","scrollX","pageXOffset","scrollY","pageYOffset","visualViewport","screenX","screenY","outerWidth","outerHeight","devicePixelRatio","clientInformation","screenLeft","screenTop","defaultStatus","defaultstatus","styleMedia","onanimationend","onanimationiteration","onanimationstart","onsearch","ontransitionend","onwebkitanimationend","onwebkitanimationiteration","onwebkitanimationstart","onwebkittransitionend","isSecureContext","onabort","onblur","oncancel","oncanplay","oncanplaythrough","onchange","onclick","onclose","oncontextmenu","oncuechange","ondblclick","ondrag","ondragend","ondragenter","ondragleave","ondragover","ondragstart","ondrop","ondurationchange","onemptied","onended","onerror","onfocus","oninput","oninvalid","onkeydown","onkeypress","onkeyup","onload","onloadeddata","onloadedmetadata","onloadstart","onmousedown","onmouseenter","onmouseleave","onmousemove","onmouseout","onmouseover","onmouseup","onmousewheel","onpause","onplay","onplaying","onprogress","onratechange","onreset","onresize","onscroll","onseeked","onseeking","onselect","onstalled","onsubmit","onsuspend","ontimeupdate","ontoggle","onvolumechange","onwaiting","onwheel","onauxclick","ongotpointercapture","onlostpointercapture","onpointerdown","onpointermove","onpointerup","onpointercancel","onpointerover","onpointerout","onpointerenter","onpointerleave","onselectstart","onselectionchange","onafterprint","onbeforeprint","onbeforeunload","onhashchange","onlanguagechange","onmessage","onmessageerror","onoffline","ononline","onpagehide","onpageshow","onpopstate","onrejectionhandled","onstorage","onunhandledrejection","onunload","performance","stop","open","alert","confirm","prompt","print","queueMicrotask","requestAnimationFrame","cancelAnimationFrame","captureEvents","releaseEvents","requestIdleCallback","cancelIdleCallback","getComputedStyle","matchMedia","moveTo","moveBy","resizeTo","resizeBy","scroll","scrollTo","scrollBy","getSelection","find","webkitRequestAnimationFrame","webkitCancelAnimationFrame","fetch","btoa","atob","setTimeout","clearTimeout","setInterval","clearInterval","createImageBitmap","onappinstalled","onbeforeinstallprompt","crypto","indexedDB","webkitStorageInfo","sessionStorage","localStorage","chrome","onformdata","onpointerrawupdate","speechSynthesis","webkitRequestFileSystem","webkitResolveLocalFileSystemURL","openDatabase","applicationCache","caches","ondevicemotion","ondeviceorientation","ondeviceorientationabsolute","WebUIListener","cr","assert","assertNotReached","assertInstanceof","$","getSVGElement","getDeepActiveElement","findAncestorByClass","findAncestor","disableTextSelectAndDrag","isRTL","getRequiredElement","queryRequiredElement","appendParam","createElementWithClassName","ensureTransitionEndEvent","scrollTopForDocument","setScrollTopForDocument","scrollLeftForDocument","setScrollLeftForDocument","HTMLEscape","elide","quoteString","listenOnce","hasKeyModifiers","isTextInputElement"];
    return Object.fromEntries(Object.entries(window).filter(([key]) => !globalKeys.includes(key)));
}


const getCircularReplacer = () => {
  const seen = new WeakSet();
  return (key, value) => {
    if (typeof value === "object" && value !== null) {
      if (seen.has(value)) {
        return;
      }
      seen.add(value);
    }
    return value;
  };
};

copy(JSON.stringify(getUserDefinedKeys(), getCircularReplacer()));

Может быть, это?:

for (var property in window)
{
    if (window.hasOwnProperty(property))
        console.log(property)
}