[in the MDN documentation about JSON.parse](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/JSON/parse#Example.3A_Using_the_reviver_parameter).
The `depth` option is used to configure the maximum depth of the `qs` library when `extended` is `true`. This allows you to limit the amount of keys that are parsed and can be useful to prevent certain types of abuse. Defaults to `32`. It is recommended to keep this value as low as possible.
## Errors
The middlewares provided by this module create errors using the
[`http-errors` module](https://www.npmjs.com/package/http-errors). The errors
will typically have a `status`/`statusCode` property that contains the suggested
HTTP response code, an `expose` property to determine if the `message` property
should be displayed to the client, a `type` property to determine the type of
error without matching against the `message`, and a `body` property containing
the read body, if available.
The following are the common errors created, though any error can come through
for various reasons.
### content encoding unsupported
This error will occur when the request had a `Content-Encoding` header that
contained an encoding but the "inflation" option was set to `false`. The
`status` property is set to `415`, the `type` property is set to
`'encoding.unsupported'`, and the `charset` property will be set to the
encoding that is unsupported.
### entity parse failed
This error will occur when the request contained an entity that could not be
parsed by the middleware. The `status` property is set to `400`, the `type`
property is set to `'entity.parse.failed'`, and the `body` property is set to
the entity value that failed parsing.
### entity verify failed
This error will occur when the request contained an entity that could not be
failed verification by the defined `verify` option. The `status` property is
set to `403`, the `type` property is set to `'entity.verify.failed'`, and the
`body` property is set to the entity value that failed verification.
### request aborted
This error will occur when the request is aborted by the client before reading
the body has finished. The `received` property will be set to the number of
bytes received before the request was aborted and the `expected` property is
set to the number of expected bytes. The `status` property is set to `400`
and `type` property is set to `'request.aborted'`.
### request entity too large
This error will occur when the request body's size is larger than the "limit"
option. The `limit` property will be set to the byte limit and the `length`
property will be set to the request body's length. The `status` property is
set to `413` and the `type` property is set to `'entity.too.large'`.
### request size did not match content length
This error will occur when the request's length did not match the length from
the `Content-Length` header. This typically occurs when the request is malformed,
typically when the `Content-Length` header was calculated based on characters
instead of bytes. The `status` property is set to `400` and the `type` property
is set to `'request.size.invalid'`.
### stream encoding should not be set
This error will occur when something called the `req.setEncoding` method prior
to this middleware. This module operates directly on bytes only and you cannot
call `req.setEncoding` when using this module. The `status` property is set to
`500` and the `type` property is set to `'stream.encoding.set'`.
### stream is not readable
This error will occur when the request is no longer readable when this middleware
attempts to read it. This typically means something other than a middleware from
this module read the request body already and the middleware was also configured to
read the same request. The `status` property is set to `500` and the `type`
property is set to `'stream.not.readable'`.
### too many parameters
This error will occur when the content of the request exceeds the configured
`parameterLimit` for the `urlencoded` parser. The `status` property is set to
`413` and the `type` property is set to `'parameters.too.many'`.
### unsupported charset "BOGUS"
This error will occur when the request had a charset parameter in the
`Content-Type` header, but the `iconv-lite` module does not support it OR the
parser does not support it. The charset is contained in the message as well
as in the `charset` property. The `status` property is set to `415`, the
`type` property is set to `'charset.unsupported'`, and the `charset` property
is set to the charset that is unsupported.
### unsupported content encoding "bogus"
This error will occur when the request had a `Content-Encoding` header that
contained an unsupported encoding. The encoding is contained in the message
as well as in the `encoding` property. The `status` property is set to `415`,
the `type` property is set to `'encoding.unsupported'`, and the `encoding`
property is set to the encoding that is unsupported.
### The input exceeded the depth
This error occurs when using `bodyParser.urlencoded` with the `extended` property set to `true` and the input exceeds the configured `depth` option. The `status` property is set to `400`. It is recommended to review the `depth` option and evaluate if it requires a higher value. When the `depth` option is set to `32` (default value), the error will not be thrown.
## Examples
### Express/Connect top-level generic
This example demonstrates adding a generic JSON and URL-encoded parser as a
top-level middleware, which will parse the bodies of all incoming requests.