How to pass values wrapped in Promise into non-async function?

Question

In a class method, I retrieved some data through an async function, this.retrieveData(). This method returns me the data which I intend to pass it to another function called renderTemplate().

async getTemplateHtml() {
   const data = await this.retrieveData()
   const html = renderTemplate(`some html template`, {stuff: data}
   return html
}

The problem, however, is that this.retrieveData() actually returns an array of Promises in the form of Promise<string>[] while the signature of renderTemplate() is renderTemplate(string, {stuff: string[]}

I cannot pass data returned from this.retrieveData() directly into the renderTemplate()'s second parameter because the elements in data are still wrapped in a Promise. I can't change the second parameter of renderTemplate() function too because it is from a npm library.

How can I somehow resolve the values wrapped in Promises in data so that I can pass it into renderTemplate() as its actual value unwrapped from its Promise?

Does `const data = await Promise.all(this.retrieveData())` do what you mean? — Ry-, May 22 '18 at 04:38

score 3 · Accepted Answer · answered May 22 '18 at 04:42

3

If retrieveData returns an array of promises, it should be:

const data = await Promise.all(this.retrieveData());

This maps an array of promises to an array of values.

answered May 22 '18 at 04:42

Estus Flask

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Just curious, what if `retrieveData()` was returning Promise instead? Do I still use Promise.all? – Carven May 22 '18 at 05:02
1

No, this would be `await this.retrieveData()`, as you originally suggested. – Estus Flask May 22 '18 at 05:24

How to pass values wrapped in Promise into non-async function?

1 Answers1