Chrome Extension: Background js cannot receive message from Popup js occasionally - google-chrome-extension

Question

There is a button on the popup. When clicked, popup.js will send a message to background.js. It works well almost all the time. But after a long time not operating chrome, when I click the button, the message is sent(alert("Start to send message") executed) but cannot be received by background.js(alert("Start to render") not executed). When I click one more, it will sometimes work. If it still doesn't work, I will click again, the third time has much more chance to success. That's very strange.
I use jquery in the popup.html, but I don't think it matter.
Javascript code in popup.js
$('#create).html(chrome.i18n.getMessage('create'))
.on('click', function(){
_current = null;
chrome.runtime.sendMessage({
cmd: 'SITEMAP_DEFINE'
});
alert("Start to send message");
window.close();
})
Javascript code in background.js
var curTabId; //current tab in which scraper is going to scraping
var devtoolPort;
var coord;
var sitemap;
var finish = false;
function sendMessage(msg) {
chrome.tabs.query({active: true, currentWindow: true}, function(tabs) {
chrome.tabs.sendMessage(tabs[0].id, msg);
});
}
//detective devtools
chrome.runtime.onConnect.addListener(function (port) {
if (port.name == "devtools-papa") {
devtoolPort = port;
}
});
//tab update
chrome.tabs.onUpdated.addListener(function(tabId, changeInfo, tab) {
if(finish === false && coord && changeInfo.status == 'loading'){
coord.onUpdate(tab);
}
})
chrome.tabs.onRemoved.addListener(function(tabId, removeInfo) {
if(finish === false && coord && removeInfo.isWindowClosing === false){
coord.onRemove(tabId);
}
})
chrome.runtime.onMessage.addListener(function(msg, sender, callback){
var p = msg.params;
//scrape
if(msg.cmd == 'START_SCRAPE'){
sitemap = p.sitemap;
if(sitemap){
finish = false;
coord = new Coordinator(sitemap, 0);
var page = coord.sitemap.pages[0];
coord.openTab(page.id, page.link);
}
}
else if(msg.cmd == 'TEST_SCRAPE'){
sitemap = p.sitemap;
if(sitemap){
chrome.tabs.query({active: true, currentWindow: true}, function(tabs) {
var tab = tabs[0];
sitemap.pages[0].link = tab.url;
finish = false;
coord = new Coordinator(sitemap, 20);
var page = coord.sitemap.pages[0];
coord.openTab(page.id, page.link);
})
}
}
else if(msg.cmd == 'SCRAPE_READY'){
print(sender);
coord.readyForScrape(sender.tab.id);
}
else if(msg.cmd == 'TAB_CLICK'){
coord.currentPage = sitemap.getPage(p.page);
}
//define
else if(msg.cmd == 'START_SELECT'){
if(msg.tabId){
chrome.tabs.sendMessage(msg.tabId, msg);
}else{
sendMessage(msg);
}
}
else if(msg.cmd == 'END_SELECT'){
if(devtoolPort){
devtoolPort.postMessage(msg);
}
sendMessage(msg);
}
else if(msg.cmd == 'SITEMAP_DEFINE'){
alert("Start to render");
var url = p && p.url;
sitemap = p && p.sitemap;
chrome.tabs.query({active: true, currentWindow: true}, function(tabs) {
var tab = tabs[0];
if(url && url != tab.url){
chrome.tabs.create({url: url}, function(newTab){
doInjectScript(newTab.id);
})
}else{
injectScript(tab.id);
}
});
}
else if(msg.cmd == 'SITEMAP_DEFINE_END'){
var _sm = p.sitemap;
chrome.tabs.query({active: true, currentWindow: true}, function(tabs) {
var tab = tabs[0];
_sm.pages[0].link = tab.url;
saveSitemap(_sm);
})
}
else if(msg.cmd == 'SITEMAP_DELETE'){
deleteSitemap(p.sitemap);
}
else if(msg.cmd == 'DEFINE_PAGE_LOADED'){
callback(sitemap);
}
else{
sendMessage(msg);
}
});
var print = function(msg){
if(curTabId){
chrome.tabs.sendMessage(curTabId, {
cmd: 'LOG',
params: msg
});
}else{
sendMessage(msg)
}
}
function saveSitemap(_sm){
var id = _sm.id;
chrome.storage.local.get("sitemaps", function(db){
var _sitemaps = db["sitemaps"];
if(!_sitemaps || !_sitemaps.length){
_sitemaps = [_sm];
}else{
var _idx = _sitemaps.findIndex(function(s){return s.id == id});
if(_idx == -1){
_sitemaps.push(_sm);
}else{
_sitemaps.splice(_idx, 1, _sm);
}
}
var _db = {'sitemaps':_sitemaps}
chrome.storage.local.set(_db, function(){
alert(chrome.i18n.getMessage('saved'));
});
})
}
function deleteSitemap(id){
chrome.storage.local.get("sitemaps", function(db){
var _sitemaps = db["sitemaps"];
var index = _sitemaps.findIndex(function(s){return s.id == id})
_sitemaps.splice(index, 1);
var _db = {'sitemaps':_sitemaps}
chrome.storage.local.set(_db, function(){
alert(chrome.i18n.getMessage('deleted'));
});
})
}
function injectScript(tabId){
var flag;
chrome.tabs.sendMessage(tabId, {
cmd: 'SELF_CHECK'
}, function(r){
flag = r;
});
setTimeout(function(){
if(flag){
chrome.tabs.executeScript(tabId, {file: "injected/define/initUI.js"}, function() {});
}else{
doInjectScript(tabId);
}
}, 200)
}
//Injected scripts will be removed once the tab reload again.
function doInjectScript(tabId){
chrome.tabs.executeScript(tabId, {file: "injected/listener.js"});
chrome.tabs.executeScript(tabId, {file: "lib/jquery/jquery-2.1.1.min.js"}, function() {
chrome.tabs.executeScript(tabId, {file: "lib/model.js"});
chrome.tabs.executeScript(tabId, {file: "lib/css-selector-generator.js"}, function() {});
chrome.tabs.executeScript(tabId, {file: "injected/SelectTool.js"}, function() {});
chrome.tabs.executeScript(tabId, {file: "injected/define/initUI.js"}, function() {});
chrome.tabs.insertCSS(tabId, {file: "injected/injected.css", runAt: "document_end"});
});
}
function createResultTab(title, fields, data){
chrome.tabs.create({url: chrome.extension.getURL('result/table.html')}, function(newTab){
var tabId = newTab.id;
setTimeout(function(){
chrome.tabs.sendMessage(tabId, {
cmd: 'RESULT',
params:{
data: data,
title: title,
fields: fields
}
});
}, 200)
})
}
Thanks in advance for your help.

Answer 1

I find the answer in official document.
If we set persistent = false, the background js will be unload when it goes idle.
{
"name": "My extension",
...
"background": {
"scripts": ["eventPage.js"],
"persistent": false
},
...
}
The document tells sending message from content script will cause background js reload. But I guess message from popup script has issue.
So either change persistent true or chrome.runtime.getBackgroundPage in popup to cause background js reload will solve this issue.