Java script code help

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const express $=$ require$("$express$")$;

const cors $=$ require$("$cors$")$;

const multer $=$ require$("$multer$")$;

const Joi $=$ require$("$joi$")$;

const mongoose $=$ require$("$mongoose$")$;

const app $=$ express$()$;

app.use$($cors$())$;

app.use$($express$.$json$())$;

app.use$($express$.$static$("$public$"))$;

const storage $=$ multer.diskStorage$(\{$

destination: $($req$,$ file, cb$)=>\{$

cb$($null$,"./$public$/$images$/")$;

$\},$

filename: $($req$,$ file, cb$)=>\{$

cb$($null$,$ Date.now$()+"-"+$ file.originalname$)$;

$\},$

$\})$;

const upload $=$ multer$(\{$ storage: storage $\})$;

const mongoURI $=$ process.env.MONGODB$\_$URI $||$ "mongodb$+$srv:$//$:@abc url$/$gearInventory$?$retryWrites$=$true&w$=$majority";

mongoose

$.$connect$($mongoURI$,\{$

useNewUrlParser: true,

useUnifiedTopology: true,

$\})$

$.$then$(()=>\{$

console.log$("$MongoDB connected successfully"$)$;

$\})$

$.$catch$(($err$)=>\{$

console.error$("$MongoDB connection error:", err$)$;

$\})$;

const gearSchema $=$ new mongoose.Schema$(\{$

name: $\{$ type: String, required: true $\},$

brand: $\{$ type: String, required: true $\},$

price: $\{$ type: Number, required: true $\},$

img$\_$name: $\{$ type: String $\},$

rating: $\{$ type: Number $\},$

features: $\{$ type: $[$String$]\},$

$\})$;

const Gear $=$ mongoose.model$("$Gear$",$ gearSchema$)$;

const itemSchema $=$ Joi.object$(\{$

name: Joi.string$().$required$(),$

brand: Joi.string$().$required$(),$

price: Joi.number$().$required$(),$

img$\_$name: Joi.string$().$optional$(),$

rating: Joi.number$().$optional$(),$

features: Joi.array$().$items$($Joi$.$string$()).$optional$(),$

$\})$;

app.get$("/",($req$,$ res$)=>\{$

res.sendFile$(\_\_$dirname $+"/$index$.$html$")$;

$\})$;

app.post$("/$api$/$upload$",$ upload.single$("$gear$"),($req$,$ res$)=>\{$

if $(!$req.file$)\{$

return res.status$(400).$send$("$No file uploaded."$)$;

$\}$

console.log$("$File uploaded successfully:", req.file$)$;

res.send$(\{$ message: "File uploaded successfully!", file: req.file $\})$;

$\})$;

app.get$("/$api$/$gear$",$ async $($req$,$ res$)=>\{$

try $\{$

const items $=$ await Gear.find$()$;

res.json$($items$)$;

$\}$ catch $($err$)\{$

console.error$("$Error fetching gear items:", err$)$;

res.status$(500).$json$(\{$ success: false, message: "Failed to fetch gear items" $\})$;

$\}$

$\})$;

app.post$("/$api$/$gear$",$ async $($req$,$ res$)=>\{$

const $\{$ error $\}=$ itemSchema.validate$($req$.$body$)$;

if $($error$)\{$

console.log$("$Validation error:", error.details$)$;

return res.status$(400).$json$(\{$ success: false, message: error.details$[0].$message $\})$;

$\}$

try $\{$

const newItem $=$ new Gear$($req$.$body$)$;

await newItem.save$()$;

console.log$("$New gear item added:", newItem$)$;

res.status$(201).$json$(\{$ success: true, newItem $\})$;

$\}$ catch $($err$)\{$

console.error$("$Error saving gear item:", err$)$;

res.status$(500).$json$(\{$ success: false, message: "Failed to add gear item" $\})$;

$\}$

$\})$;

app.put$("/$api$/$gear$/$:id$",$ async $($req$,$ res$)=>\{$

const $\{$ error $\}=$ itemSchema.validate$($req$.$body$)$;

if $($error$)\{$

console.log$("$Validation error:", error.details$)$;

return res.status$(400).$json$(\{$ success: false, message: error.details$[0].$message $\})$;

$\}$

try $\{$

const updatedItem $=$ await Gear.findByIdAndUpdate$($req$.$params.id$,$ req.body, $\{$

new: true,

$\})$;

if $(!$updatedItem$)\{$

return res.status$(404).$json$(\{$ success: false, message: "Item not found" $\})$;

$\}$

console.log$("$Gear item updated:", updatedItem$)$;

res.json$(\{$ success: true, updatedItem $\})$;

$\}$ catch $($err$)\{$

console.error$("$Error updating gear item:", err$)$;

res.status$(500).$json$(\{$ success: false, message: "Failed to update gear item" $\})$;

$\}$

$\})$;

app.delete$("/$api$/$gear$/$:id$",$ async $($req$,$ res$)=>\{$

try $\{$

const deletedItem $=$ await Gear.findByIdAndDelete$($req$.$params.id$)$;

if $(!$deletedItem$)\{$

return res.status$(404).$json$(\{$ success: false, message: "Item not found" $\})$;

$\}$

console.log$("$Gear item deleted:", deletedItem$)$;

res.json$(\{$ success: true, message: "Item deleted successfully" $\})$;

$\}$ catch $($err$)\{$

console.error$("$Error deleting gear item:", err$)$;

res.status$(500).$json$(\{$ success: false, message: "Failed to delete gear item" $\})$;

$\}$

$\})$;

const PORT $=$ process.env.PORT $||4000$;

app.listen$($PORT$,()=>\{$

console.log$(`$Listening on port $$\{$PORT$\}...`)$;

$\})$;