JavaScript 中的 Promises/Fetch：如何从文本文件中提取文本

Question

I'm working on a small program in JavaScript. Basically, I want to use Promise and fetch to extract text out of two text files. However, I can't figure out how to get the actual text out of the files. Here's my current code.

sample.txt

this is
a sample
text file.

sample2.txt

this is
the second
sample file.

index.js

function getSampleText() {

  Promise.all([
  fetch('sample.txt'),
  fetch('sample2.txt')
  ]).then(allResp => {
    let sampleResp = allResp[0];
    let sample2Resp = allResp[1];
    console.log(sampleResp);
    console.log(sample2Resp);
  })
}

Here are the Promises...how do I get the text out of these?

Answer 1

Fetch doesn't return a promise for the text of a response - it returns a promise for a Response object available after headers have been received.

This is so you can do cool things like:

• Determine how you want to read the body of the response based on the headers.
• Stream the response progressively etc.

If you want the text of the response - you can .text() the Response objects to get a promise for that:

Promise.all([
  fetch('sample.txt').then(x => x.text()),
  fetch('sample2.txt').then(x => x.text())
]).then(([sampleResp, sample2Resp]) => {
  console.log(sampleResp);
  console.log(sample2Resp);
});

Answer 2

Use async/await

async function getSampleText() {
  console.log( (await fetch('sample.txt')).text() );
  console.log( (await fetch('sample2.txt')).text() );
}