> ## Documentation Index
> Fetch the complete documentation index at: https://docs.near.org/llms.txt
> Use this file to discover all available pages before exploring further.
# Backend Authentication
> Learn how to authenticate NEAR users in your backend service by creating challenges, requesting wallet signatures, and verifying signatures.
export const Github = ({url, start, end, fname, language, withSourceLink = true}) => {
const [code, setCode] = useState(null);
function toRaw(ref) {
const fullUrl = ref.slice(ref.indexOf('https'));
const [url] = fullUrl.split('#');
const [org, repo, , branch, ...pathSeg] = new URL(url).pathname.split('/').slice(1);
return `https://raw.githubusercontent.com/${org}/${repo}/${branch}/${pathSeg.join('/')}`;
}
async function fetchCode(url, fromLine, toLine) {
let res;
if (typeof window !== 'undefined') {
const validUntil = localStorage.getItem(`${url}-until`);
if (validUntil && Number(validUntil) > Date.now()) {
res = localStorage.getItem(url);
}
}
if (!res) {
try {
res = await (await fetch(url)).text();
if (typeof window !== 'undefined') {
localStorage.setItem(url, res);
localStorage.setItem(`${url}-until`, String(Date.now() + 60000));
}
} catch {
return 'Error fetching code, please try reloading';
}
}
let body = res.split('\n');
const from = fromLine ? Number(fromLine) - 1 : 0;
const to = toLine ? Number(toLine) : body.length;
body = body.slice(from, to);
const precedingSpace = body.reduce((prev, line) => {
if (line.length === 0) return prev;
const spaces = line.match(/^\s+/);
if (spaces) return Math.min(prev, spaces[0].length);
return 0;
}, Infinity);
return body.map(line => line.slice(precedingSpace === Infinity ? 0 : precedingSpace)).join('\n');
}
function buildSourceUrl(url, start, end) {
const base = url.split('#')[0];
if (start && end) return `${base}#L${start}-L${end}`;
if (start) return `${base}#L${start}`;
return base;
}
useEffect(() => {
const rawUrl = toRaw(url);
fetchCode(rawUrl, start, end).then(res => setCode(res));
}, [url, start, end]);
const sourceUrl = buildSourceUrl(url, start, end);
const fileName = fname ?? sourceUrl.split('/').pop();
return
{code === null ?
Loading...
:
{code}
}
{withSourceLink &&
}