# validate

## Effect

Validate the detected value is legal or not.

If validate passed, return the original value or the value after processing. (Because `default` and `format` can modify the final return value.)

Otherwise, if validate failed, it will throw a `ValidateError`. The message prop of `ValdiateError` points to the failure reason. You can set some custom error messages by calling `error`.

## Arguments

* `[value]` ***(\*)*** - The value to detect, default is `undefined`.

## Returns

The original value or the value after processing.

## Example

```javascript
const schema = racoon.number().min(0);
try {
  schema.validate(2);
  // pass
} catch (error) {
  // fail
}
```