How to Introduce Delays and Pauses in Puppeteer Execution Flow?

Controlling Execution Flow in Puppeteer: Implementing Delays and Pauses

In Puppeteer, the need often arises to pause or delay execution before proceeding to subsequent lines of code. This is essential for synchronization with web pages or simulating user interactions effectively.

One common approach is using JavaScript's setTimeout function, which takes a callback and a time interval as parameters. However, as demonstrated in the code snippet provided, this method doesn't achieve the intended result within Puppeteer's context.

A solution involves leveraging Promise-based approaches. One way is to define a delay function:

function delay(time) {
   return new Promise(function(resolve) { 
       setTimeout(resolve, time)
   });
}

By invoking this function, a delay of the specified duration is introduced in the execution flow:

console.log('before waiting');
await delay(4000);
console.log('after waiting');

Puppeteer also provides a built-in waitForTimeout function that offers direct control over the pause duration:

await page.waitForTimeout(4000)

Additionally, if the desire persists to use page.evaluate for introducing delays, it's crucial to ensure that the callback function is properly resolved after the desired interval:

await page.evaluate(async() => {
    await new Promise(function(resolve) { 
           setTimeout(resolve, 1000)
    });
});

By implementing these delay techniques, you can effectively control the execution flow in Puppeteer, ensuring proper synchronization and realistic interaction with web pages.

The above is the detailed content of How to Introduce Delays and Pauses in Puppeteer Execution Flow?. For more information, please follow other related articles on the PHP Chinese website!