import { Page } from "https://deno.land/x/fresh@1.6.1/tests/deps.ts";
Waits for a function to finish evaluating in the page's context.
Examples
The Page.waitForFunction can be used to observe viewport size change:
The Page.waitForFunction can be used to observe viewport size change:
const puppeteer = require('puppeteer');
(async () => {
const browser = await puppeteer.launch();
const page = await browser.newPage();
const watchDog = page.waitForFunction('window.innerWidth < 100');
await page.setViewport({width: 50, height: 50});
await watchDog;
await browser.close();
})();
To pass arguments from node.js to the predicate of
Page.waitForFunction function:
To pass arguments from node.js to the predicate of Page.waitForFunction function:
const selector = '.foo';
await page.waitForFunction(
selector => !!document.querySelector(selector),
{},
selector
);
The predicate of Page.waitForFunction can be asynchronous too:
The predicate of Page.waitForFunction can be asynchronous too:
const username = 'github-username';
await page.waitForFunction(
async username => {
const githubResponse = await fetch(
`https://api.github.com/users/${username}`
);
const githubUser = await githubResponse.json();
// show the avatar
const img = document.createElement('img');
img.src = githubUser.avatar_url;
// wait 3 seconds
await new Promise((resolve, reject) => setTimeout(resolve, 3000));
img.remove();
},
{},
username
);
Parameters
-
Optional waiting parameters
-
polling- An interval at which thepageFunctionis executed, defaults toraf. Ifpollingis a number, then it is treated as an interval in milliseconds at which the function would be executed. If polling is a string, then it can be one of the following values: -
raf- to constantly executepageFunctioninrequestAnimationFramecallback. This is the tightest polling mode which is suitable to observe styling changes. -
mutation- to execute pageFunction on every DOM mutation. -
timeout- maximum time to wait for in milliseconds. Defaults to30000(30 seconds). Pass0to disable timeout. The default value can be changed by using the Page.setDefaultTimeout method.