Priority of code execution JavaScript NodeJS

Question

I run script on server:

const fs = require('fs');

async function loadData() {
    fs.readFile('ADDR To FILE\\cfg.json', 'utf8', (err, data) => {
        if (err) {
            console.error(err);
            return;
        }
        map = JSON.parse(data);
        console.log("1:" + serverAddr);
        serverAddr = map.serverAddr;
        console.log("2:" + serverAddr);
    });
    console.log("3:" + serverAddr);
    console.log("4:" + serverAddr);
}

var serverAddr = "NOT INIT";
console.log("5:" + serverAddr);
loadData();
console.log("6:" + serverAddr);

cfg.json file (from same folder):

{
"serverAddr":"https://google.com/"
}

And my output is:

5:NOT INIT
3:NOT INIT
4:NOT INIT
6:NOT INIT
1:NOT INIT
2:https://google.com/

What is wrong? If I add await before fs.readFile I receive message form VS Code: 'await' has no effect on the type of this expression.ts(80007)

At the beginning of my program, I need to initialize global variables using .json file from hard disc. What is wrong? Why it is not executed in order? I expect execution 1 and 2 before 3 and 4, but with ant without await, console.log() 1 and 2 are at the end of program.

Absolutely nothing is wrong. Go through the mozilla docs and get a good read on callbacks and promises. — code, Jun 21 '23 at 05:34

score 1 · Accepted Answer · answered Jun 21 '23 at 05:55

1

Change fs.readFile to fs.readFileSync

Keep in mind that these to methods can fail if you are sending a directory. Check the documentation of node here.

Also this question can help you stackoverflow

answered Jun 21 '23 at 05:55

Saumus

162
8

Yes, this is correct answer. But I don't know why await can't fix it :/ – sosnus Jun 21 '23 at 13:14

Priority of code execution JavaScript NodeJS

1 Answers1