How to wait for JavaScript to finish in playwright

Question

I am testing UI with Playwright and JavaScript. My code find an input element that can sometimes be a drop down, sometimes a text and sometimes a date. To handle this I enter value with 2 steps. First I fill the text and then click on tab key to invoke the JavaScript that formats the value in the element.

await page.fill("#myID", inputText); 
await page.keyboard.press('Tab');  // this line trigger the JS

// continue to the next element 

The problem, it is not waiting for JavaScript to finish. How can I wait for JS to finish before the code continue.

Answer 1

Using the page.waitFor... functions

There are a slew of functions that playwright offers for when certain conditions are met that start with page.waitFor (eg page.waitForFunction ). Probably page.waitForFunction is the most versatile, because you can pass a custom function that waits for a specific condition to be met.

Alternatively, use a timeout

I think you can use setTimeout with page.evaluate inside the page context to wait a bit for other JavaScript to run:

await page.evaluate(() => {
  // if this doesn't work, you can try to increase 0 to a higher number (i.e. 100)
  return new Promise((resolve) => setTimeout(resolve, 0));
});

This might be equivalent to page.waitForTimeout(0) , but I'm not sure. Note that they recommend not to use page.waitForTimeout in production.

Answer 2

You might find this useful, ( https://repl.it/join/bkgmwcjv-vladimirlisove1 ). https://developer.mozilla.org/enUS/docs/Web/JavaScript/Reference/Statements/async_function .

function resolveAfter2Seconds() {
  return new Promise(resolve => {
    setTimeout(() => {
      resolve('resolved');
    }, 2000);
  });
}

async function asyncCall() {
  console.log('calling');
  const result = await resolveAfter2Seconds();
  console.log(result);
  // expected output: "resolved"
}

asyncCall();

alternatively, found an example from freecodecamp , which appears to be simpler:

const promise = new Promise((resolve, reject) => {  

  setTimeout(function(){ 
    resolve(); // Task is completed
  }, 3000);

  return resolve;
});

promise.then(res => {
  console.log('resolved');
}).catch(err => {
    console.log(err)
});

Answer 3

I was able to resolve the problem using:

page.waitForFunction(() => Ext.Ajax.isLoading() === false );