jszip wait for creation of zip before working with data

user_17383572 0
Viewed 649

Working on a nodejs implementation of JSZip to create a zip file in binary string format and store its value in a global variable however in spite of using async/await the zipstring is being printed before the zipping process is finished,

Here is my code so far:

const JSZip = require("jszip");
const zip = new JSZip();
let s="not yet done";
let zipstring = "";
async function dozipping() {
  zip.file("Hello.txt", "Hello World\n");
  zip.generateAsync({ type: "binarystring" })
     .then(function(content) {
       console.log("doing");
       zipstring = content;
     });
}
async function status() {
  console.log(s)
  await dozipping();
  console.log(zipstring)
  s = "done";
  console.log(s)
}
status();

Expected Output

not yet done
doing 
*zipstring value*
done

Output I am currently getting

not yet done
done

doing

I am new to node and working with jszip for the 1st time and the documentation is a little confusing, sorry in advance if the question is too trivial

jszip async-await node.js javascript
2 Answers

This is because the .then from zip.generateAsync does not halt the execution. You are gonna need to use

zipstring = await zip.generateAsync(...);

Await halts the execution of an asynchronous function until the promise is resolved.

user_118779860

The reason you got nothing is promises are async and they are called once the async task is completed with the status as fulfilled or rejected. I have made some changes to it:

const zip = new JSZip();
let s="not yet done";
let zipstring = "";
async function dozipping(){
      zip.file("Hello.txt", "Hello World\n");
      try {
        console.log("doing");
        const response = await zip.generateAsync({type:"binarystring"});
        zipstring = response;
        return response;
      } catch (error) {
        console.error(error); 
      }  
}
async function status(){
   try {
    console.log(s)
    await dozipping();
    console.log(zipstring)
    s="done";
    console.log(s)
   } catch (error) {
     console.error(error);
   }
    
}
await status();

I would suggest you to first go through how promises work and how async\await should be used. They are just a syntactic sugar on it. I am attaching the link to through them.

user_70256990
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