react api, not working

my_backend/data.csv

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+Pizza,80,2020-10-10,Food
+Grape Juice,30,2020-10-12,Food
+Cinema,210,2020-10-16,Entertainment
+Java Programming book,242,2020-10-15,Academic
+Mango Juice,35,2020-10-16,Food
+Dress,2000,2020-10-25,Cloth
+Tour,2555,2020-10-29,Entertainment
+Meals,300,2020-10-30,Food
+Mobile,3500,2020-11-02,Gadgets
+Exam Fees,1245,2020-11-04,Academic

my_backend/expense.db

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+{"name":"Pizza","amount":80,"spend_date":{"$$date":1602288000000},"category":"Food","_id":"Jy0gNabH0AnEpFAg"}
+{"name":"Grape Juice","amount":30,"spend_date":{"$$date":1602460800000},"category":"Food","_id":"YHRIFoDyqszEQEFP"}
+{"name":"Cinema","amount":210,"spend_date":{"$$date":1602806400000},"category":"Entertainment","_id":"yfOTnykwFPiB6rG8"}
+{"name":"Java Programming book","amount":242,"spend_date":{"$$date":1602720000000},"category":"Academic","_id":"8p3NsLJ9f3hPqykd"}
+{"name":"Mango Juice","amount":35,"spend_date":{"$$date":1602806400000},"category":"Food","_id":"bSbRHvIa0fZUtesd"}
+{"name":"Dress","amount":2000,"spend_date":{"$$date":1603584000000},"category":"Cloth","_id":"QYcaRnMvFLZ5Z4Xh"}
+{"name":"Tour","amount":2555,"spend_date":{"$$date":1603929600000},"category":"Entertainment","_id":"c02ECRHEBREKSKC9"}
+{"name":"Meals","amount":300,"spend_date":{"$$date":1604016000000},"category":"Food","_id":"RdZ9OweF69kWFvEd"}
+{"name":"Mobile","amount":3500,"spend_date":{"$$date":1604275200000},"category":"Gadgets","_id":"zCPsWaJZSdoTMhaO"}
+{"name":"Exam Fees","amount":1245,"spend_date":{"$$date":1604448000000},"category":"Academic","_id":"A43S4mxKaCr1RWX6"}

my_backend/expensedb.js

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+var store = require("nedb")
+var fs = require('fs');
+var expenses = new store({ filename: "expense.db", autoload: true })
+expenses.find({}, function (err, docs) {
+if (docs.length == 0) {
+loadExpenses();
+}
+})
+function loadExpenses() {
+readCsv("data.csv", function (data) {
+console.log(data);
+data.forEach(function (rec, idx) {
+item = {}
+item.name = rec[0];
+item.amount = parseFloat(rec[1]);
+item.spend_date = new Date(rec[2]);
+item.category = rec[3];
+expenses.insert(item, function (err, doc) {
+console.log('Inserted', doc.item_name, 'with ID', doc._id);
+})
+})
+})
+}
+function readCsv(file, callback) {
+fs.readFile(file, 'utf-8', function (err, data) {
+if (err) throw err;
+var lines = data.split('\r\n');
+var result = lines.map(function (line) {
+return line.split(',');
+});
+callback(result);
+});
+}
+module.exports = expenses

my_backend/server.js

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+var express = require("express")
+var cors = require('cors')
+var expenseStore = require("./expensedb.js")
+var app = express()
+app.use(cors());
+var bodyParser = require("body-parser");
+app.use(bodyParser.urlencoded({ extended: false }));
+app.use(bodyParser.json());
+var HTTP_PORT = 8000
+app.listen(HTTP_PORT, () => {
+ console.log("Server running on port %PORT%".replace("%PORT%", HTTP_PORT))
+});
+app.get("/", (req, res, next) => {
+ res.json({ "message": "Ok" })
+});
+app.get("/api/expenses", (req, res, next) => {
+ expenseStore.find({}, function (err, docs) {
+  res.json(docs);
+ });
+});
+app.get("/api/expense/:id", (req, res, next) => {
+ var id = req.params.id;
+ expenseStore.find({ _id: id }, function (err, docs) {
+ res.json(docs);
+ })
+});
+app.post("/api/expense/", (req, res, next) => {
+ var errors = []
+ if (!req.body.item) {
+ errors.push("No item specified");
+ }
+ var data = {
+ name: req.body.name,
+ amount: req.body.amount,
+ category: req.body.category,
+ spend_date: req.body.spend_date,
+ }
+ expenseStore.insert(data, function (err, docs) {
+ return res.json(docs);
+ });
+})
+app.put("/api/expense/:id", (req, res, next) => {
+ var id = req.params.id;
+ var errors = []
+ if (!req.body.item) {
+ errors.push("No item specified");
+ }
+ var data = {
+ _id: id,
+ name: req.body.name,
+ amount: req.body.amount,
+ category: req.body.category,
+ spend_date: req.body.spend_date,
+ }
+ expenseStore.update( { _id: id }, data, function (err, docs) {
+ return res.json(data);
+ });
+})
+app.delete("/api/expense/:id", (req, res, next) => {
+ var id = req.params.id;
+ expenseStore.remove({ _id: id }, function (err, numDeleted) {
+ res.json({ "message": "deleted" })
+ });
+})
+app.use(function (req, res) {
+ res.status(404);
+});