SoundCloud - Sort comments by timestamp - Userscript fix

// ==UserScript==
// @name         Soundcloud: Sort comments by timestamp
// @description  Sort comments by timestamp on Soundcloud
// @include      *soundcloud.com/*
// @grant        none
// @run-at       document-idle
// @namespace    https://greasyfork.org/users/4252
// @version      0.0.3
// ==/UserScript==

var SortButton = document.createElement("button");
SortButton.type = "button";
SortButton.className = "sort-button sc-button sc-button-medium sc-button-responsive";
SortButton.style = "float: right; margin-bottom: 6px;";
SortButton.innerHTML = "Sort by timestamp";
SortButton.onclick = sortcomments;

// window.onload doesn't work for soundcloud which is AJAX
// popstate event doesn't work reliably either.
// So let's use XHR as a proxy for page load event
// Basic AJAX interceptor by hijacking XMLHttpRequest.prototype.open
(function() {
  XMLHttpRequest.prototype.__open = XMLHttpRequest.prototype.open;
  XMLHttpRequest.prototype.open = function() {
    this.addEventListener('load', function() {
      if(this.readyState !== 4) return;
      if(this.status !== 200) return;
      if(/\/(tracks)/.test(this.responseURL)) {
        appendSortButton();
      }
    });
    XMLHttpRequest.prototype.__open.apply(this, arguments);
  };
})();

function appendSortButton() {
    if (document.getElementsByClassName("commentsList__title").length && !document.getElementsByClassName("sort-button")[0]) {
       console.info("Added sort button!");
       document.getElementsByClassName("commentsList__title")[0].appendChild(SortButton);
    }
}

function sortcomments() {
    if (document.getElementsByClassName("paging-eof").length === 0) {
        alert("Please scroll all the way to the bottom so that all comments load before running this script");
        return;
    }

    var commentContainer = document.getElementsByClassName("lazyLoadingList__list")[0];
    var allcomments = [].slice.call(commentContainer.children);
    k = 0.01; //decimal to stick at end of timestamp so that threads (replies) stay together
    for (i = 0; i < allcomments.length; i++) {
        if (allcomments[i].firstChild.classList.contains("isReply")) {
            allcomments[i].setAttribute("timestamp4sort", getTimestampInSeconds(allcomments[i]) + k);
            k = k + 0.01; //theoretically correctly sort 100 consecutive replies
        } else {
            allcomments[i].setAttribute("timestamp4sort", getTimestampInSeconds(allcomments[i]));
            k = 0.01; //reset
        }
    }

    allcomments.sort(compare);

    while (commentContainer.lastChild) {
        commentContainer.removeChild(commentContainer.lastChild);
    }

    for (i = 0; i < allcomments.length; i++) {
        commentContainer.appendChild(allcomments[i]);
    }

    console.info("Comments sorted successfully");
}


function compare(a, b) {
    var avalue = parseFloat(a.getAttribute("timestamp4sort"));
    var bvalue = parseFloat(b.getAttribute("timestamp4sort"));
    if (avalue < bvalue)
        return -1;
    if (avalue > bvalue)
        return 1;
    return 0;
}

function hmsToSecondsOnly(str) { //This function handles "HH:MM:SS" as well as "MM:SS" or "SS".
    var p = str.split(':'),
        s = 0,
        m = 1;

    while (p.length > 0) {
        s += m * parseInt(p.pop(), 10);
        m *= 60;
    }

    return s;
}

function getTimestampInSeconds(licomment) { //takes  the <li> element of a comment. returns an integer

    if (licomment.getElementsByClassName("commentItem__timestamp").length !== 0) {
        return hmsToSecondsOnly(licomment.getElementsByClassName("commentItem__timestamp")[0].innerHTML.replace("says at ", "").slice(0, -1)); //we slice of the last character to change "1:32:25:" to "1:32:25"
    } else {
        return 0;
    }
}