How to Access Google Photos API with Javascript using google-api-javascript-client and read JSON data?

I am very new to using API and getting JSON data using OAuth. Could anybody help me? I am trying to access clients google photos and read them. These code snippets are from google photos documentation. I modified it but still having error: "Failed to load resource: the server responded with a status of 401 ()" and "Uncaught {error: "idpiframe_initialization_failed", details: "Not a valid origin for the client: http://127.0.0.…itelist this origin for your project's client ID."}" Thank you!!!

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.3/jquery.min.js"></script>
<script async defer src="https://apis.google.com/js/api.js"
        onload="this.onload=function(){};handleClientLoad()"
        onreadystatechange="if (this.readyState === 'complete') this.onload()">
</script>

<script>
    var GoogleAuth;
    var SCOPE = 'https://www.googleapis.com/auth/drive.photos.readonly';

    function handleClientLoad() {
        // Load the API's client and auth2 modules.
        // Call the initClient function after the modules load.
        gapi.load('client:auth2', initClient);
    }

    function initClient() {
        // Retrieve the discovery document for version 3 of Google Drive API.
        // In practice, your app can retrieve one or more discovery documents.
        var discoveryUrl = 'https://www.googleapis.com/discovery/v1/apis/photos/v1/rest';

        // Initialize the gapi.client object, which app uses to make API requests.
        // Get API key and client ID from API Console.
        // 'scope' field specifies space-delimited list of access scopes.
        gapi.client.init({
            'apiKey': 'XXXXXXXXXXXX',
            'discoveryDocs': [discoveryUrl],
            'clientId': 'XXXXXXXXXXXXXXXXXX',
            'scope': SCOPE
        }).then(function () {
            GoogleAuth = gapi.auth2.getAuthInstance();

            // Listen for sign-in state changes.
            GoogleAuth.isSignedIn.listen(updateSigninStatus);

            // Handle initial sign-in state. (Determine if user is already signed in.)
            var user = GoogleAuth.currentUser.get();
            setSigninStatus();

            // Call handleAuthClick function when user clicks on
            //      "Sign In/Authorize" button.
            $('#sign-in-or-out-button').click(function () {
                handleAuthClick();
            });
            $('#revoke-access-button').click(function () {
                revokeAccess();
            });
        });
    }

    function handleAuthClick() {
        if (GoogleAuth.isSignedIn.get()) {
            // User is authorized and has clicked 'Sign out' button.
            GoogleAuth.signOut();
        } else {
            // User is not signed in. Start Google auth flow.
            GoogleAuth.signIn();
        }
    }

    function revokeAccess() {
        GoogleAuth.disconnect();
    }

    function setSigninStatus(isSignedIn) {
        var user = GoogleAuth.currentUser.get();
        var isAuthorized = user.hasGrantedScopes(SCOPE);
        if (isAuthorized) {
            $('#sign-in-or-out-button').html('Sign out');
            $('#revoke-access-button').css('display', 'inline-block');
            $('#auth-status').html('You are currently signed in and have granted ' +
                'access to this app.');
        } else {
            $('#sign-in-or-out-button').html('Sign In/Authorize');
            $('#revoke-access-button').css('display', 'none');
            $('#auth-status').html('You have not authorized this app or you are ' +
                'signed out.');
        }
    }

    function updateSigninStatus(isSignedIn) {
        setSigninStatus();
    }
</script>

<button id="sign-in-or-out-button"
        style="margin-left: 25px">Sign In/Authorize
</button>
<button id="revoke-access-button"
        style="display: none; margin-left: 25px">Revoke access
</button>

<div id="auth-status" style="display: inline; padding-left: 25px"></div>

Solution

use this link to get more details

On right side there is button Execute, on click that button you will get all photos , you can also find code just clicking a icon right side square icon of text Try this API, a popup will open, click on JAVASCRIPT Tab , you will find code

https://developers.google.com/photos/library/reference/rest/v1/mediaItems/search