"sync is not defined" error showing in chrome extension - google-chrome

Question

sync is not defined" error showing in chrome extension while have used storage permission.please acknowledge me where is error and how
will solve message : "sync is not defined" stack : "ReferenceError:
sync is not defined↵ at eval (eval at
(http://localhost:46950/app/popup.js:31:9), :1:1)↵ at
HTMLInputElement.
(http://localhost:46950/app/popup.js:31:9)↵ at
HTMLInputElement.dispatch
(http://localhost:46950/app/img/jquery-3.2.1.min.js:6:12417)↵ at
HTMLInputElement.q.handle
//manifest.json
{
"manifest_version": 2,
"name": "One-click ",
"description": "This extension demonstrates a browser .",
"version": "1.0",
"app": {
"launch": {
"local_path": "popup.html"
}
},
"browser_action": {
"default_icon": "img/icon.png",
"default_popup": "popup.html"
},
"background": {
"scripts": [ "popup.js", "img/jquery-3.2.1.min.js" ],
"persistent": false
},
"content_scripts": [
{
"css": [ "img/bootstrap.min.css"],
"js": [ "app/popup.js", "img/jquery-3.2.1.min.js" ],
"matches": [ "http://*/*", "https://*/*" ]
}
],
"permissions": [
"activeTab",
"storage",
"tabs",
"identity"
]
}
//popup.js
chrome.storage.sync.set({ 'data':"helloset" }, function () {
alert("saved");
});

Answer 1

*method* is not defined errors usually means the method was being called while the library wasn't yet loaded or there's really no such method. In your case, I think it's the former. Looking at the IzumiSy/manifest.json sync example, you need to use document.body.onload first then call that function like:
// popup.js
document.body.onload = function() {
chrome.storage.sync.get("data", function(items) {
if (!chrome.runtime.error) {
console.log(items);
document.getElementById("data").innerText = items.data;
}
});
}

Answer 2

if you need to save data locally you can use
document.body.onload = function() {
chrome.storage.sync.get("data", function(items) {
if (!chrome.runtime.error) {
console.log(items);
document.getElementById("data").innerText = items.data;
}
});
}
document.getElementById("set").onclick = function() {
var d = document.getElementById("text").value;
chrome.storage.sync.set({ "data" : d }, function() {
if (chrome.runtime.error) {
console.log("Runtime error.");
}
});
window.close();
}