Question
We have some routing logic that kicks you to the homepage if you dont have a JWT_TOKEN set... I want to set this before the page loads/before the js is invoked.
how do i do this ?
Solution
You have to register localStorage item like this:
await page.evaluate(() => {
localStorage.setItem('token', 'example-token');
});
You should do it after page page.goto - browser must have an url to register local storage item on it. After this, enter the same page once again, this time token should be here before the page is loaded.
Here is a fully working example:
const puppeteer = require('puppeteer');
const http = require('http');
const html = `
<html>
<body>
<div id="element"></div>
<script>
document.getElementById('element').innerHTML =
localStorage.getItem('token') ? 'signed' : 'not signed';
</script>
</body>
</html>`;
http
.createServer((req, res) => {
res.writeHead(200, { 'Content-Type': 'text/html' });
res.write(html);
res.end();
})
.listen(8080);
(async () => {
const browser = await puppeteer.launch();
const page = await browser.newPage();
await page.goto('http://localhost:8080/');
await page.evaluate(() => {
localStorage.setItem('token', 'example-token');
});
await page.goto('http://localhost:8080/');
const text = await page.evaluate(
() => document.querySelector('#element').textContent
);
console.log(text);
await browser.close();
process.exit(0);
})();
Solution
There's some discussion about this in Puppeteer's GitHub issues.
You can load a page on the domain, set your localStorage, then go to the actual page you want to load with localStorage ready. You can also intercept the first url load to return instantly instead of actually load the page, potentially saving a lot of time.
const doSomePuppeteerThings = async () => {
const url = 'http://example.com/';
const browser = await puppeteer.launch();
const localStorage = { storageKey: 'storageValue' };
await setDomainLocalStorage(browser, url, localStorage);
const page = await browser.newPage();
// do your actual puppeteer things now
};
const setDomainLocalStorage = async (browser, url, values) => {
const page = await browser.newPage();
await page.setRequestInterception(true);
page.on('request', r => {
r.respond({
status: 200,
contentType: 'text/plain',
body: 'tweak me.',
});
});
await page.goto(url);
await page.evaluate(values => {
for (const key in values) {
localStorage.setItem(key, values[key]);
}
}, values);
await page.close();
};