Remove Signup Bar From Twitter

remove_signup_bar.user.js

// ==UserScript==
// @name         Remove Signup Bar
// @namespace    http://tampermonkey.net/
// @version      1.0
// @description  Remove the "sign up for twitter!" bar that blocks 20% of the content on every Twitter page
// @author       Kevin
// @match        https://twitter.com/*
// @icon         https://www.google.com/s2/favicons?domain=twitter.com
// @grant        none
// ==/UserScript==

(function() {
    'use strict';

    const signupSelector = "[data-testid=signup]";
    const followSelector = "[aria-label^='Follow']";

    //distance between a node and the root.
    function height(node){
        let x = 0;
        while(node.parentNode != null){
            node = node.parentNode;
            x += 1;
        }
        return x;
    }

    //lowest node in the tree that is the ancestor of both arguments.
    function lowest_common_ancestor(a,b){
        let a_height = height(a);
        let b_height = height(b);
        while (a_height > b_height){
            a = a.parentNode;
            a_height -= 1;
        }
        while (b_height > a_height){
            b = b.parentNode;
            b_height -= 1;
        }
        while (a != b){
            a = a.parentNode;
            b = b.parentNode;
        }
        return a;
    }

    //like removeChild, but removes every node between ancestor and descendant
    function removeLineage(ancestor, descendant){
        while(descendant.parentNode != ancestor){
            descendant = descendant.parentNode;
        }
        ancestor.removeChild(descendant);
    }

    //Deletes the largest possible branch of the DOM that erases nodeToRemove without erasing nodeToKeep.
    function prune(nodeToRemove, nodeToKeep){
        let ancestor = lowest_common_ancestor(nodeToRemove, nodeToKeep);
        removeLineage(ancestor, nodeToRemove);
    }

    //call `callback` shortly after an element matching `selector` is added to the DOM.
    function onExists(selector, callback){
        let node = document.querySelector(selector);
        if (node != null){
            callback(node);
        }
        else{
            setTimeout(onExists, 100, selector, callback);
        }
    }

    onExists(signupSelector, function(signupButton){
        //console.log("found Signup button.");
        onExists(followSelector, function(followButton){
            //console.log("found follow button.");
            prune(signupButton, followButton);
        });
    })
})();