@fobx/core

Getting Started

The behavior of @fobx/core is almost identical to that of mobx with respect to the critical path of behavior. Meaning it passes all of the mobx unit tests with respect to observable values, computed values, reactions and transactions (once API differences have been accounted for).

Because of this functional equivalence, almost all of the mobx documentation and stack overflow questions found for mobx are applicable to @fobx/core. The following are the notable differences that are needed in order to get started:

1. Fobx has two methods for creating observable state, observable and observableBox functions.

   import { observable, observableBox } from "@fobx/core"
   
   const num = observableBox(1)
   const str = observableBox("hello fobx")
   const bool = observableBox(true)
   const arr = observable([1, 2, 3])
   const map = observable(
     new Map([
       ["a", "a"],
       ["b", "b"],
     ]),
   )
   const set = observable(new Set([1, 2, 3]))
   const obj = observable({ a: 1, b: 2 })
   class A {
     a = 1
     constructor() {
       this.b = 2
       // acts like mobx's makeAutoObservable
       observable(this)
     }
   }

2. observableBox is needed when making a primitive type observable. When this happens you get and set the value through the .value property.

   import { observableBox } from "@fobx/core"
   
   const a = observableBox(1)
   console.log(a.value) // prints 1
   a.value = 5
   console.log(a.value) // prints 5

3. Observable values are tracked immediately instead of waiting until the end of the reaction body.

   const o = observableBox(0);
   const seen: number[] = [];
   
   autorun(() => {
      seen.push(o.value);
      if (o.value < 3) o.value += 1;
   });
   
   console.log(seen); // prints [0,1,2,3] ... mobx will have [0]
   o.value += 1;
   console.log(seen) // prints [0,1,2,3,4] ... mobx will have [0,2,3,4]

TODO List

1. observableObject needs to handle property add + delete?
2. Find and address any TODO: comments in the code.

Notes

1. Array functions with callbacks (filter, forEach, every, etc...) return the non-proxied array as the 3rd argument of the callback instead of the proxy. This is for performance related reasons. Consumers have access to the proxied array (they're calling the function on it) if they need to do something with.