我需要在下面的對象中創(chuàng)建一個包含所有鍵（而不是值）的數(shù)組，其中鍵以_下劃線開頭...在下面的代碼片段中，我試圖getSubscriptions()返回["_foo1", "_foo2"]let myObj = {  foo0: 'test',  _foo1: 'test',  _foo2: 'test',  foo3: 'test',};function getSubscriptions(obj, cb) {    // should return ["_foo1", "_foo2"]    let ret = ["foo1", "_foo2"];    return cb(ret);}getSubscriptions(myObj, (ret) => {    if (match(ret, ["_foo1", "_foo2"]) ) {         $('.nope').hide();        return $('.works').show();     }    $('.nope').show();    $('.works').hide();});function match(arr1, arr2) {    if(arr1.length !== arr2.length) { return false; }     for(var i = arr1.length; i--;) {         if(arr1[i] !== arr2[i]) { return false;}      }    return true; }body {    background: #333;    color: #4ac388;    padding: 2em;    font-family: monospace;    font-size: 19px;}.nope {  color: #ce4242;}.container div{  padding: 1em;  border: 3px dotted;}<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script><div class="container">    <div class="works">It Works!</div>    <div class="nope">    Doesn't Work...</div></div>