Create search in options page

Fixes #242

lib/search.js

@@ -0,0 +1,51 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+(function(){
+	"use strict";
+	
+	var scope;
+	if ((typeof exports) !== "undefined"){
+		scope = exports;
+	}
+	else {
+		window.scope.search = {};
+		scope = window.scope.search;
+	}
+	
+	const texts = [];
+	
+	scope.register = function(text, content){
+		texts.push({text: text.toLowerCase(), content});
+	};
+	scope.search = function(search){
+		search = search.toLowerCase();
+		const result = [];
+		texts.forEach(function(text){
+			if (text.text.indexOf(search) !== -1){
+				result.push(text.content);
+			}
+		});
+		return result;
+	};
+	const searchListeners = [];
+	scope.init = function(){
+		const node = document.createElement("input");
+		node.id = "search";
+		node.placeholder = browser.i18n.getMessage("search");
+		window.setTimeout(() => node.focus(), 1);
+		let lastResults = [];
+		node.addEventListener("input", function(){
+			const search = this.value;
+			const results = search? scope.search(search): [];
+			searchListeners.forEach(function(callback){
+				callback({search, results, lastResults});
+			});
+			lastResults = results;
+		});
+		return node;
+	};
+	scope.on = function(callback){
+		searchListeners.push(callback);
+	};
+}());