fiber/docs/api/middleware/expvar.md
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📚 Docs: Fix typos, and make middleware documentation more consistent (#2408)
Fix typos, and make docs more consistent
This fixes several typos in the ISSUE_TEMPLATES, as well as improve
their readability, also makes the documentation markdowns more
consistent
2023-04-10 10:48:12 +08:00

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---
id: expvar
title: ExpVar
---
Expvar middleware for [Fiber](https://github.com/gofiber/fiber) that serves via its HTTP server runtime exposed variants in the JSON format. The package is typically only imported for the side effect of registering its HTTP handlers. The handled path is `/debug/vars`.
## Signatures
```go
func New() fiber.Handler
```
## Examples
Import the middleware package that is part of the Fiber web framework
```go
import (
"github.com/gofiber/fiber/v2"
expvarmw "github.com/gofiber/fiber/v2/middleware/expvar"
)
```
After you initiate your Fiber app, you can use the following possibilities:
```go
var count = expvar.NewInt("count")
app.Use(expvarmw.New())
app.Get("/", func(c *fiber.Ctx) error {
count.Add(1)
return c.SendString(fmt.Sprintf("hello expvar count %d", count.Value()))
})
```
Visit path `/debug/vars` to see all vars and use query `r=key` to filter exposed variables.
```bash
curl 127.0.0.1:3000
hello expvar count 1
curl 127.0.0.1:3000/debug/vars
{
"cmdline": ["xxx"],
"count": 1,
"expvarHandlerCalls": 33,
"expvarRegexpErrors": 0,
"memstats": {...}
}
curl 127.0.0.1:3000/debug/vars?r=c
{
"cmdline": ["xxx"],
"count": 1
}
```
## Config
```go
// Config defines the config for middleware.
type Config struct {
// Next defines a function to skip this middleware when returned true.
//
// Optional. Default: nil
Next func(c *fiber.Ctx) bool
}
```
## Default Config
```go
var ConfigDefault = Config{
Next: nil,
}
```