Converts a JSON string into an object of the given type.

The type can be String, Number, BigInt, Boolean, Date, Array, Object or any class constructor (including Error types). If the class has a static fromJSON(data: any): T method, it will be invoked to create the instance (unless the parsed data is null, which will be skipped without further processing).

This function generally does not perform loose conversion between types, for example, parseAs('"123"', Number) will not work, it only reverses to the same type before the data are encoded.

However, for compatibility support, there are some exceptions allowed, which are:

• string => Date
• number or string => bigint
• array => Buffer or TypedArray (e.g. Uint8Array), when the data only contains integers.
• object => Buffer or TypedArray (e.g. Uint8Array), if the data are encoded by JSON.stringify().
• customized in fromJSON()

If the data cannot be converted to the given type, this function returns null.