How to reset global variable on every new HTTP POST request? - node.js

Question

We are actually tring to read a csv file as input and throw out the corresponding results for the data in CSV file.
For every new http POST request, new result is being appended to the existing data in array(productDetails), but I want to flush the old data in array for every new request.
let productDetails=[];
router.get('/add-product',(req,res,next)=>{
res.sendFile(path.join(__dirname,'../','views','add-product.html'))
})
router.post('/add-product',(req,res,next)=>{
if (!req.files || Object.keys(req.files).length === 0) {
return res.status(400).send('No files were uploaded.');
}
else {
var sampleFile=req.files.file;
sampleFile.mv('././uploads/'+sampleFile.name,function(err){
if(err){
return res.status(500).send(err);
}
})
readFile('././uploads/'+sampleFile.name,'utf-8',(err,fileContent)=>{
if(err){
console.log(err); // Do something to handle the error or just throw it
throw new Error(err);
}
const jsonObj = csvjson.toObject(fileContent);
jsonObj.forEach(obj=>{
data.forEach(obj1=>{
if(obj.Make ==obj1.Make && obj.Manufacture == obj1.Manufacture && obj.Product==obj1.Product){
productDetails.push({
product:obj1.Product,
price:obj1.Price,
manufacture:obj1.Manufacture,
make:obj1.Make
})
}
})
})
})
}
res.redirect('/');
})
exports.routes=router;
exports.productDetails=productDetails;

Answer 1

You Can try by adding this line
router.post('/add-product',(req,res,next)=>{
productDetails=[];
//YOUR CODE
})

Answer 2

I think you need a function variable rather than a global variable for producrDetails, so if you define your variable inside the POST call it will work according to your requirements and start will an empty productDetails array on every POST call.
router.post('/add-product',(req,res,next)=>{
let productDetails=[]
// CODE
jsonObj.forEach(obj=>{
data.forEach(obj1=>{
if(obj.Make ==obj1.Make && obj.Manufacture == obj1.Manufacture && obj.Product==obj1.Product){
productDetails.push({
product:obj1.Product,
price:obj1.Price,
manufacture:obj1.Manufacture,
make:obj1.Make
})
}
})
})
}