Exception handling when backend URL resource is not reachable - javascript

I have the below js function in my vue.js single file component, I want to try catch the exception when the URL requested by axios.post is not reachable. I have put the whole code in try block but I still don't get the alert I have put in the catch block.
Updated using .catch
deploySelected: function(){
this.showStatus = true ;
// animate open the status window.
$("#status_update").animate({height: '500'})
var url = "http://test-web-machine01.localsite.com:5060/scripts/request_deploy";
axios.post(url)
.then(response => {
if (typeof response.data.reason != "undefined"){
alert("Recieved Status: " + response.data.status + ",\nReason: " + response.data.reason);
}
var req_id = response.data.result.request_id;
this.statusMessage = "Initiating deployment of Scripts for Request ID: " + req_id ;
})
.catch((err) => alert(err))
console.log(url);
}

I got it working like this: .catch((err) => alert(err)) thanks #Jaromanda

Related

how find which element cause error in promis.map and log it in console, or skip it by code?

I using following code, but some URL from URL List, get 500 Error because of structure of the page.
I get the error exactly on .map((htmlOnePage, index) => line when some URLs page not valid, and the flow control of program goes at Catch Part. How I can find which URL is invalid?
const requestPromise = require('request-promise');
const Promise = require('bluebird');
const cheerio = require('cheerio');
for (var i = 1; i <= 250; i++) {
p = "https://mywebsite.com/" + i.toString()
urls[i - 1] = p
}
Promise.map(urls, requestPromise)
.map((htmlOnePage, index) => {
const $ = cheerio.load(htmlOnePage);
$('.txtSearch1').each(function() {
var h = "";
h = $(this).text()
h = h.replace(/(\r\n|\n|\r)/gm, "")
html44.push(h)
})
shareTuple[urls[index]] = html44;
html44 = []
fs.writeFileSync("data.json", JSON.stringify(shareTuple))
}, {
concurrency: 1
})
.then()
.catch((e) => console.log('We encountered an error' + e));
in other word how I can show which URL get into catch?
You should add try catch phrases inside all iterating functions to pin point the problem. and do the logging for every one based on op that they are catching.
For example i would wrap it like this:
try {
const $ = cheerio.load(htmlOnePage);
$('.txtSearch1').each(function () {
try {
var h="";
h=$(this).text()
h= h.replace(/(\r\n|\n|\r)/gm, "")
html44.push (h)
}catch (error) {
console.log('Error in getting p text');
console.log(error);
}
} catch (error) {
console.log('Error in loading'+ htmlOnePage);
console.log(error);
}
You can break down the error more by looking up through error object values to find the problem if you want to manualy remove it.
The other way to programaticaly remove it is to try doing the request for the page after creating it and also wrapping it in try catch. If it throws an exception you can add in catch to remove it from the list.
That text before console log of error is just so you can see where it broke.
Use a wrapper around requestPromise that catches the error. Note, the return undefined is not really needed. It's just for clarification, that in case of an error nothing is returned.
const requestPromise = require('request-promise');
....
const noThrowRequest = async (url) => {
try {
return await requestPromise(url);
} catch (e) {
return undefined;
}
}
Or if you prefer .then().catch() you can do it as follows
const noThrowRequest = (url) => {
return requestPromise(url)
.then(result => { return result; })
.catch(e => { return undefined; });
}
And then use that wrapper instead of requestPromise and check whether the current result valid or not. I don't know what you want to do in case of an invalid result, so I just return from the callback without any further ado. Adapt that if necessary.
Promise.map(urls, noThrowRequest)
.map((htmlOnePage, index) => {
if (htmlOnePage === undefined) {
console.log(`there was an error at index ${index}`);
return; //stop callback for erronous indexes.
}
...
}

Promise.all fetch continue executing after throwing error?

I am trying to fetch JSON data from the WordPress Developer Reference site. I need to search a keyword without knowing if it's a function, class, hook, or method, which is part of the url I need to fetch. So I'm using Promise.all to cycle through all possible urls. It works if the response.status <= 299, throwing the error immediately, and if the response is ok, then it continues to .then. Fine, but occasionally it will return an ok status if the JSON exists and only returns an empty array. So I need to check if the JSON data is an empty array, which I can't seem to do in the first part. I can only check in the second part as far as I know. And if it throws the error it doesn't continue trying the other urls. Any suggestions?
var keyword = 'AtomParser';
const refs = ['function', 'hook', 'class', 'method'];
// Store the promises
let promises = [];
// Cycle through each type until we find one we're looking for
for (let t = 0; t < refs.length; t++) {
const url =
'https://developer.wordpress.org/wp-json/wp/v2/wp-parser-' +
refs[t] +
'?search=' +
keyword;
// console.log(url);
promises.push(fetch(url));
}
Promise.all(promises)
.then(function(response) {
console.log(response[0]);
// Get the status
console.log('Status code: ' + response[0].status);
if (response[0].status <= 299) {
// The API call was successful!
return response[0].json();
} else {
throw new Error('Broken link status code: ' + response[0].status);
}
})
.then(function(data) {
// This is the HTML from our response as a text string
console.log(data);
// Make sure we have data
if (data.length == 0) {
throw new Error('Empty Array');
}
// ref
const reference = data[0];
// Only continue if not null or empty
if (reference !== null && reference !== undefined && data.length > 0) {
// Success
// Return what I want from the reference
}
})
.catch(function handleError(error) {
console.log('Error' + error);
});
Is there some way to get the JSON data in the first part so I can check if it's in an array while I'm checking the response status?
I would recommend encapsulating the success / failure logic for individual requests, then you can determine all the resolved and rejected responses based on the result of that encapsulation.
For example
const checkKeyword = async (ref, keyword) => {
const params = new URLSearchParams({ search: keyword });
const res = await fetch(
`https://developer.wordpress.org/wp-json/wp/v2/wp-parser-${encodeURIComponent(
ref
)}?${params}`
);
if (!res.ok) {
throw new Error(`${res.status}: ${await res.text()}`);
}
const data = await res.json();
if (data.length === 0) {
throw new Error(`Empty results for '${ref}'`);
}
return { ref, data };
};
Now you can use something like Promise.any() or Promise.allSettled() to find the first successful request or all successful requests, respectively
const keyword = "AtomParser";
const refs = ["function", "hook", "class", "method"];
const promises = refs.map((ref) => checkKeyword(ref, keyword));
// First success
Promise.any(promises)
.then(({ ref, data }) => {
console.log(ref, data);
})
.catch(console.error);
// All successes
Promise.allSettled(promises)
.then((responses) =>
responses.reduce(
(arr, { status, value }) =>
status === "fulfilled" ? [...arr, value] : arr,
[]
)
)
.then((results) => {
// results has all the successful responses
});
For whatever reason I couldn't get Phil's answer to work, so I ended up doing the following which works fine for me. (This is for a discord bot in case you're wondering what the other stuff is all about).
var keyword = 'AtomParser';
const refs = ['function', 'hook', 'class', 'method'];
// Store the successful result or error
let final: any[] = [];
let finalError = '';
// Cycle through each type until we find one we're looking for
for (let t = 0; t < refs.length; t++) {
const url =
'https://developer.wordpress.org/wp-json/wp/v2/wp-parser-' +
refs[t] +
'?search=' +
keyword;
console.log(url);
// Try to fetch it
await fetch(url)
.then(function (response) {
console.log(response);
// Get the status
console.log('Status code: ' + response.status);
if (response.status > 299) {
finalError = '`' + refs[t] + '` does not exist.';
throw new Error(finalError);
} else {
// The API call was successful!
return response.json();
}
})
.then(function (data) {
// This is the HTML from our response as a text string
console.log(data);
// Make sure we have data
if (data.length == 0) {
finalError = "Sorry, I couldn't find `" + keyword + '`';
throw new Error(finalError);
}
// Only continue if not null or empty
if (data[0] !== null && data[0] !== undefined && data.length > 0) {
for (let d = 0; d < data.length; d++) {
// Add it to the final array
final.push(data[d]);
}
}
})
.catch(function handleError(error) {
console.log(error);
});
}
if (final.length > 0) {
for (let f = 0; f < final.length; f++) {
// ref
const reference = final[f];
// Get the link
const link = reference.link;
// Get the title
var title = reference.title.rendered;
title = excerpt.replace('>', '>');
// Get the excerpt
var excerpt = reference.excerpt.rendered;
excerpt = excerpt.replace('<p>', '');
excerpt = excerpt.replace('</p>', '');
excerpt = excerpt.replace('<b>', '**');
excerpt = excerpt.replace('</b>', '**');
console.log(excerpt);
message.reply(
new discord.Embed({
title: `${title}`,
url: link,
description: `${excerpt}\n\n`,
footer: {
text: `WordPress Developer Code Reference\nhttps://developer.wordpress.org/`,
},
})
);
}
} else if (finalError != '') {
message.reply(finalError);
} else {
message.reply('Something went wrong...');
}
wp module
#Phil's answer puts you on the right track but I want to expand on some of his ideas. Use of URLSearchParamas is great but you can improve by using the high-level URL API and forego encodeURIComponent and constructing search params manually. Notice I'm putting this code in its own wp module so I can separate concerns more easily. We don't want all of this code leaking into your main program.
// wp.js
import { fetch } from "whatwg-fetch" // or your chosen implementation
const baseURL = "https://developer.wordpress.org"
async function search1(path, query) {
const u = new URL(path, baseURL)
u.searchParams.set("search", query)
const result = await fetch(u)
if (!result.ok) throw Error(`Search failed (${result.status}): ${u}`)
return result.json()
}
search1 searches one path, but we can write search to search all the necessary paths. I don't think there's any reason to get fancy with each path here, so just write them out -
// wp.js (continued)
function search(query) {
const endpoints = [
"/wp-json/wp/v2/wp-parser-function",
"/wp-json/wp/v2/wp-parser-hook",
"/wp-json/wp/v2/wp-parser-class",
"/wp-json/wp/v2/wp-parser-method"
]
return Promise
.all(endpoints.map(e => search1(e, query)))
.then(results => results.flat())
}
export { search }
main module
Notice we only exported search as search1 is internal to the wp module. Let's see how we can use it in our main module now -
// main.js
import { search } from "./wp.js"
for (const result of await search("database"))
if(result.guid.rendered)
console.log(`${result.title.rendered}\n${result.guid.rendered}\n`)
In this example, we first search for "database" -
wp_should_replace_insecure_home_url()
https://developer.wordpress.org/reference/functions/wp_should_replace_insecure_home_url/
wp_delete_signup_on_user_delete()
https://developer.wordpress.org/reference/functions/wp_delete_signup_on_user_delete/
get_post_datetime()
https://developer.wordpress.org/reference/functions/get_post_datetime/
wp_ajax_health_check_get_sizes()
https://developer.wordpress.org/reference/functions/wp_ajax_health_check_get_sizes/
wp_should_replace_insecure_home_url
https://developer.wordpress.org/reference/hooks/wp_should_replace_insecure_home_url/
comments_pre_query
https://developer.wordpress.org/reference/hooks/comments_pre_query/
users_pre_query
https://developer.wordpress.org/reference/hooks/users_pre_query/
WP_Object_Cache
http://developer.wordpress.org/reference/classes/wp_object_cache/
wpdb
http://developer.wordpress.org/reference/classes/wpdb/
WP_REST_Menu_Items_Controller::prepare_item_for_database()
https://developer.wordpress.org/reference/classes/wp_rest_menu_items_controller/prepare_item_for_database/
WP_REST_Global_Styles_Controller::prepare_item_for_database()
https://developer.wordpress.org/reference/classes/wp_rest_global_styles_controller/prepare_item_for_database/
WP_REST_Menus_Controller::prepare_item_for_database()
https://developer.wordpress.org/reference/classes/wp_rest_menus_controller/prepare_item_for_database/
WP_REST_Templates_Controller::prepare_item_for_database()
https://developer.wordpress.org/reference/classes/wp_rest_templates_controller/prepare_item_for_database/
WP_REST_Application_Passwords_Controller::prepare_item_for_database()
https://developer.wordpress.org/reference/classes/wp_rest_application_passwords_controller/prepare_item_for_database/
wpdb::db_server_info()
https://developer.wordpress.org/reference/classes/wpdb/db_server_info/
WP_REST_Attachments_Controller::insert_attachment()
https://developer.wordpress.org/reference/classes/wp_rest_attachments_controller/insert_attachment/
WP_Debug_Data::get_database_size()
https://developer.wordpress.org/reference/classes/wp_debug_data/get_database_size/
WP_REST_Meta_Fields::update_multi_meta_value()
https://developer.wordpress.org/method/wp_rest_meta_fields/update_multi_meta_value/
another search example
Now let's search for "image" -
for (const result of await search("image"))
if(result.guid.rendered)
console.log(`${result.title.rendered}\n${result.guid.rendered}\n`)
get_adjacent_image_link()
https://developer.wordpress.org/reference/functions/get_adjacent_image_link/
get_next_image_link()
https://developer.wordpress.org/reference/functions/get_next_image_link/
get_previous_image_link()
https://developer.wordpress.org/reference/functions/get_previous_image_link/
wp_robots_max_image_preview_large()
https://developer.wordpress.org/reference/functions/wp_robots_max_image_preview_large/
wp_getimagesize()
https://developer.wordpress.org/reference/functions/wp_getimagesize/
is_gd_image()
https://developer.wordpress.org/reference/functions/is_gd_image/
wp_show_heic_upload_error()
https://developer.wordpress.org/reference/functions/wp_show_heic_upload_error/
wp_image_src_get_dimensions()
https://developer.wordpress.org/reference/functions/wp_image_src_get_dimensions/
wp_image_file_matches_image_meta()
https://developer.wordpress.org/reference/functions/wp_image_file_matches_image_meta/
_wp_check_existing_file_names()
https://developer.wordpress.org/reference/functions/_wp_check_existing_file_names/
edit_custom_thumbnail_sizes
https://developer.wordpress.org/reference/hooks/edit_custom_thumbnail_sizes/
get_header_image_tag_attributes
https://developer.wordpress.org/reference/hooks/get_header_image_tag_attributes/
image_editor_output_format
https://developer.wordpress.org/reference/hooks/image_editor_output_format/
wp_image_src_get_dimensions
https://developer.wordpress.org/reference/hooks/wp_image_src_get_dimensions/
wp_get_attachment_image
https://developer.wordpress.org/reference/hooks/wp_get_attachment_image/
image_sideload_extensions
https://developer.wordpress.org/reference/hooks/image_sideload_extensions/
wp_edited_image_metadata
https://developer.wordpress.org/reference/hooks/wp_edited_image_metadata/
wp_img_tag_add_loading_attr
https://developer.wordpress.org/reference/hooks/wp_img_tag_add_loading_attr/
wp_image_file_matches_image_meta
https://developer.wordpress.org/reference/hooks/wp_image_file_matches_image_meta/
get_custom_logo_image_attributes
https://developer.wordpress.org/reference/hooks/get_custom_logo_image_attributes/
Custom_Image_Header
http://developer.wordpress.org/reference/classes/custom_image_header/
WP_Image_Editor_Imagick
http://developer.wordpress.org/reference/classes/wp_image_editor_imagick/
WP_Embed
http://developer.wordpress.org/reference/classes/wp_embed/
WP_Image_Editor
http://developer.wordpress.org/reference/classes/wp_image_editor/
WP_Customize_Background_Image_Setting
http://developer.wordpress.org/reference/classes/wp_customize_background_image_setting/
WP_Customize_Header_Image_Setting
http://developer.wordpress.org/reference/classes/wp_customize_header_image_setting/
WP_Image_Editor_GD
http://developer.wordpress.org/reference/classes/wp_image_editor_gd/
WP_Customize_Header_Image_Control
http://developer.wordpress.org/reference/classes/wp_customize_header_image_control/
WP_REST_Server::add_image_to_index()
https://developer.wordpress.org/reference/classes/wp_rest_server/add_image_to_index/
WP_REST_URL_Details_Controller::get_image()
https://developer.wordpress.org/reference/classes/wp_rest_url_details_controller/get_image/
WP_Image_Editor::get_default_quality()
https://developer.wordpress.org/reference/classes/wp_image_editor/get_default_quality/
WP_Theme_JSON::get_blocks_metadata()
https://developer.wordpress.org/reference/classes/wp_theme_json/get_blocks_metadata/
WP_Image_Editor_Imagick::pdf_load_source()
https://developer.wordpress.org/reference/classes/wp_image_editor_imagick/pdf_load_source/
WP_Image_Editor_Imagick::write_image()
https://developer.wordpress.org/reference/classes/wp_image_editor_imagick/write_image/
WP_Image_Editor_Imagick::maybe_exif_rotate()
https://developer.wordpress.org/reference/classes/wp_image_editor_imagick/maybe_exif_rotate/
WP_Image_Editor_Imagick::make_subsize()
https://developer.wordpress.org/reference/classes/wp_image_editor_imagick/make_subsize/
WP_Image_Editor_GD::make_subsize()
https://developer.wordpress.org/reference/classes/wp_image_editor_gd/make_subsize/
empty search result
Searching for "zzz" will yield no results -
for (const result of await search("zzz"))
if(result.guid.rendered)
console.log(`${result.title.rendered}\n${result.guid.rendered}\n`)
<empty result>

Access to body response on Cache with Javascript

I'm working on a node.js and i want to store some data on cache.
The request is stored successfully.
const version = "3.4.3";
caches.open('v' + version)
.then(async cache => {
await cache.add('/getTranslations');
const data = await cache.match('/getTranslations');
});
Here is what endpoint returns:
app.get("/getTranslations", (req, res) => {
res.status(200).send(/*Here is the object shown
on the next picture and what i want to read from cache*/);
});
I have this on cache on chrome:
I'm trying to access to what is show on the preview but I'm not able to get it.
Using
// In my case the name of the cache is 'v4'
const c = await caches.open('v4');
// Here finds the 7 requests.
await c.keys()
// Here i get the request but i can't not get the data I'm looking for.
await c.match('/getTranslations')
Here i found the solution myself with javascript:
Using as an example what is shown on the question request would be '/getTranslations' and version would be '4'.
cachePetition: async function (version: string, request: string) {
let body = -1;
return caches.open('v' + version).then(async cache => {
// Function to get the cached data
const writeRequestToCache = async () => {
console.log("[Cache] Getting '" + request + "' ...");
await cache.add(request);
const result = await cache.match(request);
return result.json();
}
let data = await cache.match(request);
// If there is no data in the cache, get it from the server
if (data == undefined) {
console.log("[Cache] '" + request + "' not found.");
body = await writeRequestToCache();
} else {
body = await data.json();
// If you can't access to the body of the petition ask it again. This is a workaround for the cache bug.
if (body == undefined) {
console.log("[Cache] '" + request + "' data corrupted. Getting it again...");
body = await writeRequestToCache();
} else {
console.log("[Cache] '" + request + "' found.");
}
}
return body;
});
}

Unable to save fetched data in Jquery

I'm working on my front-end, and I've arrived at a roadblock. I'm trying to fetch data from my back-end, and it is actually fetching the data. But only after everything else? I'll show you.
$(function(){
function GetURLId() {
var url = window.location.href;
var path = url.substring(url.lastIndexOf('/') + 1);
var id = path.substring(path.lastIndexOf('?id=') + 4, path.lastIndexOf("?id") + 5)
return id;
}
var url = 'https://localhost:5001/api/rental/byId/' + GetURLId();
fetch(url)
.then((resp) => resp.json())
.then(function(data) {
Object.keys(data).forEach(key => {
console.log(`${key}: ${data[key]}`);
})
});
});
So first I get which id I'm working with out of the URL. Then where the problem lays is the code under it. I'm able to fetch my data as it console.logs this:
id: 2
status: "Open"
damage: true
So the data does actually fetch from my back-end. But now, everytime I try to save the data it goes undefined. I've tried:
$(function(){
var rental = []; // Added an array
var url = 'https://localhost:5001/api/rental/byId/' + GetURLId();
fetch(url)
.then((resp) => resp.json())
.then(function(data) {
Object.keys(data).forEach(key => {
console.log(`${key}: ${data[key]}`);
rental.push(rental[key] = data[key]);
})
});
console.log(rental['id']); // Returns undefined
});
And:
var rental = []; // Added an array outside of the function
$(function(){
var url = 'https://localhost:5001/api/rental/byId/' + GetURLId();
fetch(url)
.then((resp) => resp.json())
.then(function(data) {
Object.keys(data).forEach(key => {
console.log(`${key}: ${data[key]}`);
rental.push(rental[key] = data[key]);
})
});
console.log(rental['id']); // Returns undefined
});
But! With the last one where the rental is outside of the function, I can actually call it in the console. And in the console it actually does return the value.
Inside Console:
> rental["id"]
< 2
Lastly I've tried to check the value of the key and value inside of the fetch, like this:
$(function(){
var url = 'https://localhost:5001/api/rental/byId/' + GetURLId();
fetch(url)
.then((resp) => resp.json())
.then(function(data) {
Object.keys(data).forEach(key => {
if(key == "status" && data[key] != "Reserved") {
console.log(`${key}: ${data[key]}`); // Returns damage: undefined 3 times
}
})
});
});
But this as well doesn't work. It returns damage: undefined 3 times in console.
So if anyone knows what is going on here it would be awesome!
Thanks alot in advance.
Fetch requests are asynchronous. This means that when you call fetch it might take a while to complete it, so JavaScript allows the rest of the code to continue without blocking. So logging anything to the console before your request has finished will obviously result in an empty array.
Also, Arrays are index-, not name based in JavaScript. However, because arrays are essentially objects it still works, but you should never do the following below.
var rental = [];
rental['id'] = 'foo';
console.log(rental['id']);
Instead use a plain object which is meant to be used that way.
var rental = {};
rental['id'] = 'foo';
console.log(rental['id']);
In your last example you seem to do everything just fine. Are you sure your fetched data does not have a value of undefined in its structure? It would help to see what the data looks like.
The answer: 2 errors in my code.
- First I didn't properly account for the asynchronous nature of the code.
- Second, when trying to fix it with another then block and executing my code in there. I didn't return a value in the proceeding then block, but the forEach instead.
fetch(url)
.then(resp => resp.json())
.then(data => {
var rentalStatus;
Object.keys(data).forEach(key => {
rental[key] = data[key];
if(key == "status") {
rentalStatus = data[key];
}
})
return rentalStatus;
})
.then(rentalStatus => {
console.log(rental["id"]); // This does return the id now!
if(rentalStatus == "Reserved") {
$("#assign-items").removeClass("d-none");
}
}).catch(error => {
console.log("Error:" + error);
});

JSON.parse: unexpected character when fetching data from NodeJS server

I'm trying to fetch the data from my localhost Node server but I still getting this "JSON.parse: unexpected character at line 1 column 1 of the JSON data". It works fine when I fetch from https://randomuser.me/api/?results=10, but not for my own JSON array.
server.js (backend)
//RENDER HTML PAGE TO GET THE RESULTS
app.get('/device', isLoggedIn, function(req,res)
{
fs.readFile('./public/list.html', 'utf8', (err, data)=> {
res.write(data);
res.end();
});
});
//GENERATE MY JSON ARRAY
app.get('/mydevices', isLoggedIn, function(req,res)
{
connection.query("\
SELECT `dispositivos`.`nome` \
FROM `dispositivos` JOIN `usuarios` \
ON `usuarios`.`id` = `dispositivos`.`user_id` AND `user_id`='" + req.user.id + "'", (err,result)=>
{
res.json({'results': result});
// console.log(result)
});
});
controller.js (frontend - NOT working for my JSON)
window.onload = function(){
function createNode(element) {
return document.createElement(element);
}
function append(parent, el) {
return parent.appendChild(el);
}
const ul = document.getElementById('mydevices');
const url = 'http://localhost:777/mydevices';
fetch(url)
.then((resp) => resp.json())
.then(function(data) {
let devices = data.results;
return devices.map(function(device) {
let li = createNode('li'),
// img = createNode('img'),
span = createNode('span');
// img.src = device.picture.medium;
span.innerHTML = `${device.nome}`;
// append(li, img);
append(li, span);
append(ul, li);
})
})
.catch(function(error) {
console.log(error);
});
};
controller.js (frontend - WORKING for randomuser.me API)
window.onload = function(){
function createNode(element) {
return document.createElement(element);
}
function append(parent, el) {
return parent.appendChild(el);
}
const ul = document.getElementById('authors');
const url = 'https://randomuser.me/api/?results=10';
fetch(url)
.then((resp) => resp.json())
.then(function(data) {
let authors = data.results;
return authors.map(function(author) {
let li = createNode('li'),
img = createNode('img'),
span = createNode('span');
img.src = author.picture.medium;
span.innerHTML = `${author.name.first} ${author.name.last}`;
append(li, img);
append(li, span);
append(ul, li);
})
})
.catch(function(error) {
console.log(error);
});
};
In the rendered html I have id="devices" (of course I change it to "authors" when I want to use randomuser API).
"unexpected character at line 1 column 1 of the JSON data" always means the result isn't JSON, and almost always means (in the web context) that you're getting an error page instead.
Two issues:
(The main issue.) You're trying to make a cross-origin request (to http://localhost:777, but from some other origin, I'm guessing http://localhost:80 or similar), but not issuing the necessary CORS headers to enable the call from the origin you're making the call from. In contrast, https://randomuser.me enables requests from all origins.
(Not the main issue.) You're not checking that the request succeeded. This is (in my view) a failure of the fetch API, it has a major footgun in this regard I see fired here on SO almost every day. (Details in my blog post on it.). Add:
.then(resp => {
if (!resp.ok) {
throw new Error(resp.status);
}
})
...before your .then(resp => resp.json()).

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