NodeJS: Is there a way by which i can save the value returned by a promise and can access this variable from another file

Question

I have a asynchronous function (a promise), which reads an xml file and give a map of keys and value, if the promise is resolved. I need this map throughout my project. So i want to read this xml file only once, probably at the start of my project and save the map in a variable. And i want to use the variable in different files of my project. Is there any way by which i can achieve this?

Its like, i want to use that variable, not in the same js file, but in a different js file. — Rithu Krishna, Jul 23 '17 at 17:05
Just [save the promise](https://stackoverflow.com/q/28763057/1048572) and access it anywhere you want. — Bergi, Jul 23 '17 at 17:29
To save the value, you can put it in an object with global scope, or better to save it in a static variable. So you can import/ require it else where (in any other file) and use it. — Tasmine Rout, Jul 23 '17 at 18:05

score 0 · Answer 1 · answered Jul 23 '17 at 17:25

0

You can define the functions in files to expect a parameter, use Promise.all() to load the files, pass the function reference from requested files to .then() within .then() chained to Promise.all()

const promise = Promise.resolve("do stuff");

promise.then(res => {
  Promise.all([fetch("loadFile1.js").then(res => res.text())
  /* , fetch("loadFile2.js")*/])
    .then(function(files) {
      let script = document.createElement("script");
      script.textContent = files[0];
      document.body.appendChild(script);
      promise.then(loadFile)
    })
});

where loadFiles1.js contains a function loadFile

function loadFile(data) {
  console.log(data);
}

plnkr http://plnkr.co/edit/SQzakbP936rEgnEzsP8R?p=preview

answered Jul 23 '17 at 17:25

guest271314

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This sounds like an implementation of a module loader, not the xml cache that the OP asked about. – Bergi Jul 23 '17 at 21:54
@Bergi _"This sounds like an implementation of a module loader, not the xml cache that the OP asked about."_ How so? `promise` returns the XML the OP inquires about having access to throughout code - after loading _"And i want to use the variable in different files of my project"_ – guest271314 Jul 23 '17 at 21:56
@Bergi Not too familiar with terms used to describe code. The code at Answer should perform both parts of requirement described at OP. – guest271314 Jul 23 '17 at 22:03
I believe this solution is backwards. The OP probably already has a system in place that loads the various files of the project. Also it doesn't scale well with individual dependencies - your code only works if all files depend only on the single `promise`. – Bergi Jul 23 '17 at 22:31
@Bergi No, the solution is not backwards. Perhaps you are reading the requirement backwards. The entire premise of the Question is that OP needs a variable to be defined which references XML. The XML needs to come first, then OP can load other files. Or, the files do not do stuff until the `Promise` which fetches XML is fulfilled. Yes, all other files do depend on the variable referencing the XML to be defined first _" I need this map throughout my project. So i want to read this xml file only once, probably at the start of my project and save the map in a variable."_ – guest271314 Jul 23 '17 at 22:37
@Bergi If you post an Answer given your interpretation of the requirement the OP will surely have a solution, from either perspective – guest271314 Jul 23 '17 at 22:41

NodeJS: Is there a way by which i can save the value returned by a promise and can access this variable from another file

1 Answers1