封装async函数中await page.goto返回值与直接调用该方法返回值不一致问题

Hey there! Let's break down why you're seeing null when using your gotoUrl wrapper, but getting the right result when calling page.goto directly.

First, let's diagnose the core issues #

Your problem likely stems from one of these two scenarios:

1. Missing return value in the catch block
   When page.goto throws an error (like a failed navigation), your gotoUrl function's catch block only logs the error but doesn't return anything. This means the function will implicitly return undefined, which you might be misreading as null in the console. When you call page.goto directly, any error would throw immediately (instead of being swallowed), so you either don't hit the error case or notice it right away.

2. page variable is out of scope in gotoUrl
   If gotoUrl is defined in a different scope than where your page object was created (e.g., page is a local variable in another async function, but gotoUrl is global), then page will be undefined inside gotoUrl. Calling page.goto would throw an error, trigger the catch block, and leave you with an undefined return value (again, appearing as null).

Another small thing to check: you might be confusing the HTTPResponse object returned by page.goto with the actual page URL. The response object contains the URL (via response.url()), but it's not the URL string itself.

Fixes to try #

Let's address these issues step by step:

1. Fix the error handling in gotoUrl

Add a clear return value in the catch block so you know when navigation fails, and optionally return the URL directly if that's what you need:

// Option 1: Return the full response object, with explicit null on failure
async function gotoUrl(page, release) { 
  try { 
    const response = await page.goto(release.url, {waitUntil: 'networkidle0'});
    return response;
  } catch (e) { 
    console.error('Navigation failed:', e); 
    return null; // Explicitly return null for failed navigations
  } 
}

// Option 2: Return just the URL string (if that's what you actually need)
async function gotoUrl(page, release) { 
  try { 
    const response = await page.goto(release.url, {waitUntil: 'networkidle0'});
    return response ? response.url() : null;
  } catch (e) { 
    console.error('Navigation failed:', e); 
    return null;
  } 
}

2. Ensure page is accessible to gotoUrl

Pass page as a parameter to gotoUrl to avoid scope issues. This makes your function more portable and avoids relying on global variables:

// When calling the function, pass the page object
for (let i = 0; i < jsonObjSplit.length; i++) { 
  const chgNum = getChangeTicketNum(i); 
  console.log(chgNum);
  const release = getReleaseObj(i, chgNum); 
  console.log(release);
  // Pass page to gotoUrl here
  const result = await gotoUrl(page, release); 
  console.log(result);
}

3. Optimize your loop code

You're calling getChangeTicketNum and getReleaseObj twice per iteration—let's clean that up to avoid redundant work:

for (let i = 0; i < jsonObjSplit.length; i++) { 
  const chgNum = getChangeTicketNum(i); 
  console.log(chgNum);
  
  const release = getReleaseObj(i, chgNum); 
  console.log(release);
  
  const response = await gotoUrl(page, release); 
  // Log the URL directly if that's what you want
  console.log(response ? response.url() : 'Navigation failed');
}

That should resolve the null issue and make your code more robust.

内容的提问来源于stack exchange，提问作者JustReflektor