Make `Set` and `Get` method consistent about react-native-mmkv HOT 6 CLOSED

it was a good insight for me because I was not really aware about the byte sizes before.

This is also not true, lol. What if is-mmkv-2fast is false? The contains method will return true then 😄

maybe because I've playing AsyncStorage too long that I keep use set and delete method for boolean purpose 🤔

since it's all about the byte sizes concern, I can't complain anymore. 🤣

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Set

When passing a number to set, I can see that it is a number, so the type number is implied.

Get

When reading something from the storage (which is just bytes/binary), I don't know how the type is stored. There is no type information as you could overwrite it with any type, and it is also more lightweight/performant if it does not have any type information stored. So in this case you need to specify how you interpret the type to be read.

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When reading something from the storage (which is just bytes/binary), I don't know how the type is stored.

if so, why don't let store all value as string? since there's only 3 types (string, number, boolean), I think it's more lightweight/performant because the type always string (it would be different if react-native-mmkv also can store Map and Array).

an example of the simplification I was thinking of:

storage.set('user.name', 'Marc') 
// storage.get('user.name') 

storage.set('user.age', '21')
// storage.get('user.age')
// if dev **really** need to convert it as number, use `Number(storage.get('user.age'))` instead.

storage.set('is-mmkv-2fast', 'true')
// for boolean, i think `storage.contains('is-mmkv-2fast')` is enough, don't need for redundant method

would you mind considerating it @mrousavy ?

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if so, why don't let store all value as string? since there's only 3 types (string, number, boolean), I think it's more lightweight/performant because the type always string

No, why would it be more lightweight or performant to store a number or a boolean as a string?

1. Number

A number in JavaScript is represented as a 64-bit float (aka "double"), meaning it takes up 8 bytes.

The number 1 takes up 8 bytes, the number 812735 does take up 8 bytes, the number 541.5357235 takes up 8 bytes, even the number 179769313486231570814527423731704356798070567525844996598917476803157260780028538760589558632766878171540458953514382464234321326889464182768467546703537516986049910576551282076245490090389328944075868508455133942304583236903222948165808559332123348274797826204144723168738177180919299881250404026184124858368 is 8 bytes.

Strings in JavaScript are usually 2 bytes or 5 bytes (depending if they are unicode or not), so if you were to represent this as a string, the string "1" would be 2 bytes, the string "812735" would be 12 bytes, the string "541.5357235" would be 22 bytes, and the string "179769313486231570814527423731704356798070567525844996598917476803157260780028538760589558632766878171540458953514382464234321326889464182768467546703537516986049910576551282076245490090389328944075868508455133942304583236903222948165808559332123348274797826204144723168738177180919299881250404026184124858368" would be 618 bytes.

It goes without saying that this would be a huge waste of space.

2. Boolean

A boolean in JavaScript is represented with 1 byte. The string "true" would be 8 bytes, and "false" would be 10 bytes. This is another waste of space.

3. Efficiency

Reading a single boolean (00000001 in binary) is much more efficient than reading the binary values of the string, then decoding it into a UTF-8/UTF-16 character sequence.

Same goes for numbers.

4. Practicality

If you store a number or a boolean, you want to store a number or a boolean. Not a string. Example:

const isDarkMode = storage.getBoolean('is.dark')
const color = isDarkMode ? 'black' : 'white'

Now if we had strings:

const isDarkModeString = storage.getBoolean('is.dark')
const isDarkMode = isDarkModeString == 'true'
const color = isDarkMode ? 'black' : 'white'

This would be really annoying as you always need a separate cast. Or what if it is True instead of true? Or 1 instead of true?

With all of that said, I think it's pretty obvious that storing every value as a string is not a good idea.

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for boolean, i think storage.contains('is-mmkv-2fast') is enough, don't need for redundant method

This is also not true, lol. What if is-mmkv-2fast is false? The contains method will return true then 😄

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if dev really need to convert it as number, use Number(storage.get('user.age')) instead.

What else do you want to do with user.age? Age is a number, not a string - in 100% of the cases when you store a number you also want to read it as a number, not a string.

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