I was trying to read and file by using a function and need to print that data from main code. Below shown is my code.
getJsonData().then(function (jsonData) {
console.log(jsonData)
})
function getJsonData(){
var fs = require('fs');
var XLSX = require('xlsx');
let contents = fs.readFileSync("test.json");
let jsonData = JSON.parse(contents);
return jsonData ;
}
Ok first of All, that function isn't a promise, so you can't use .then. Here is how you would turn this code into a promise:
var fs = require('fs');
var XLSX = require('xlsx');
function getJsonData(){
return new Promise((resolve, reject) => {
let contents = fs.readFileSync("test.json");
if(contents == "undefined") {
reject("File contains no contents");
} else {
let jsonData = JSON.parse(contents);
resolve(jsonData);
}
})
}
You would then use the function like you did in the question:
getJsonData().then(function (jsonData) {
console.log(jsonData)
})
readFileSync doesn't return a promise, so you can't use .then() after getJsonData(), as getJsonData() doesn't return a promise.
You can simply use:
const fs = require('fs');
const results = getJsonData();
console.log(results);
function getJsonData() {
const contents = fs.readFileSync("test.json");
return JSON.parse(contents);
}
readFileSync is asnychronous, it will block execution until the content is read