Press '/' to focus on the first search input on any webpage

SlashSearch.js

// ==UserScript==
// @name         Slash Jumps to Search
// @namespace    http://tampermonkey.net/
// @version      1.0
// @description  Press '/' to focus on the first search input on any webpage
// @author       Mariven
// @match        *://*/*
// @exclude      *://*google.com*
// @exclude      *://*youtube.com*
// @grant        none
// ==/UserScript==

(function() {
    'use strict';

	const isSlash = (e) => e.key === '/' || e.keyCode === 191;
	const activeInput = (el = document.activeElement) => ['INPUT', 'TEXTAREA'].includes(el.tagName) || el.isContentEditable;
	const inputSelectors = `
				input[type="search"],
                input[name*="search" i],
                input[placeholder*="search" i],
                input[aria-label*="search" i],
                form input[type="text"],
                input[type="text"]`;

    document.addEventListener('keydown', function(e) {
        if (isSlash(e)) {
            if (activeInput())
                return;
            e.preventDefault(); // prevents '/' from being typed
            const searchInput = document.querySelector(inputSelectors);
            if (searchInput)
                searchInput.focus();
        }
    });
})();