Having trouble to run the Google Drive API on Google Chrome - google-drive-api

Question

Here I am again still trying to run my platform with the Google Drive API. It works perfectly on Mozilla, but it does not work on Google Chrome. I keep getting this error:
Uncaught TypeError: Cannot read property 'init' of undefined
at initClient (google_drive:370)
at api.js:15
at fa (api.js:8)
at A (api.js:15)
at Array.r. (api.js:15)
at Object.x. [as loaded_0] (api.js:15)
at cb=gapi.loaded_0:1
Here is the code I am running:
var CLIENT_ID = '';
var API_KEY = '';
// Array of API discovery doc URLs for APIs used by the quickstart
var DISCOVERY_DOCS = ["https://www.googleapis.com/discovery/v1/apis/drive/v3/rest"];
// Authorization scopes required by the API; multiple scopes can be
// included, separated by spaces.
var SCOPES = 'https://www.googleapis.com/auth/drive.readonly';
var authorizeButton = document.getElementById('authorize_button');
var signoutButton = document.getElementById('signout_button');
var localdriveButton = document.getElementById('localdrive_button');
var FILES = {};
function handleClientLoad() {
setTimeout(function(){ gapi.load('client:auth2', initClient); }, 3000);
}
function initClient() {
gapi.client.init({
apiKey: API_KEY,
clientId: CLIENT_ID,
discoveryDocs: DISCOVERY_DOCS,
scope: SCOPES
}).then(function () {
// Listen for sign-in state changes.
gapi.auth2.getAuthInstance().isSignedIn.listen(updateSigninStatus);
// Handle the initial sign-in state.
updateSigninStatus(gapi.auth2.getAuthInstance().isSignedIn.get());
authorizeButton.onclick = handleAuthClick();
signoutButton.onclick = handleSignoutClick();
}, function(error) {
console.log(JSON.stringify(error, null, 2));
});
return gapi;
}
Does anyone have any idea of what problem I might have and how to fix it?