How to return promise object as array of strings?

alex deralu 0
Viewed 46

I have the following code

const link =
  "https://www.daft.ie/property-for-rent/ireland?location=dublin&location=dublin-city&sort=publishDateDesc";

async function getLinks(url) {
  return fetch(url)
    .then((res) => res.text())
    .then((html) => {
      const $ = cheerio.load(html);
      const sel = '[data-testid="results"] a[href]';
      var links = [...$(sel)].map((e) => e.attribs.href);
      return Promise.all(links);
    });
}

getLinks(link).then(function(links) {
  console.log(links);
});

This returns me an object array like this

[
  '/for-rent/apartment-105-cabra-road-phibsborough-dublin-7/4071977',
  '/for-rent/apartment-weavers-hall-leopardstown-dublin-18/4073220',
]

I would like this to be returned as array of strings so I can perform comparison operations more easily and so I can store the array in a variable.

Also I want know how to use await in this

I want it to work like this but it fails currently

const a = await getLinks(link1);
const b = await getLinks(link2);

where a and b contain string arrays.

How can I do this?

cheerio promise javascript
2 Answers

You cannot call await unless it is within an async context. It's like calling then on a non-Promise object. You could wrap it within an anonymous async method such as:

(async () => {
  const a = await getLinks(link1);
  const b = await getLinks(link2);
  // do something
})()

...or using Promise.all:

(async () => {
  const [a, b] = await Promise.all([getLinks(link1), getLinks(link2)]);
  // do something
})()

It is also strongly recommended and a best practice to wrap await usage within a try...catch block in case the Promise fails.

Steve Hynding0

You can get the first part of the URL with the built-in URL api:

const link = "https://www.daft.ie/property-for-rent/ireland?location=dublin&location=dublin-city&sort=publishDateDesc";
  
const url = new URL(link);

console.log(url.protocol + "//" + url.host);

Then you can append the links you get to this:

const url = new URL(link);

const a = await getLinks(url.protocol + "//" + url.host + link1);
const b = await getLinks(url.protocol + "//" + url.host + link2);

If you want to use await at the top level, and if the environment doesn't support top-level await, then yes you'll have to create an async IIFE:

(async () => {
    // your code
})();
caTS0
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