Using PHP-like magic methods in JS-1024programmer

Javascript magic methods

This script uses Proxy to implement magic methods similar to PHP in Javascript.

Example

You can use it like this:

const Foo = magicMethods  (class Foo {
   constructor () {
     this.bar = 'Bar'
   }
   __get(name) {
     return `[[${name}]]`
   }
 })
 const foo = new Foo
 foo. bar // "Bar"
 foo.baz // "[[baz]]"

If you are using a Javascript compiler like Babel with decorators enabled, you can also use magicMethods functions as decorators:

@magicMethods
 class Foo {
   //...
 }

Magic methods supported

Given a class Class and instance, the following are the magic methods supported by this script:

__get (name)

Called when an attempt is made to access instance[name] and name is not an attribute of instance.

Note: In PHP, checking for the existence of name in an instance does not use any custom __isset() methods.

__set(name, value)

This method is called when an attempt is made to use instance[name] = … and the instance does not have a name attribute set.

__isset(name)

This method is called when an attempt is made to check whether name exists by calling name in instance.

__unset(name)

This method is called when trying to unset the name attribute via delete instance[name].

Other methods

The following magic methods are supported by this script, but not in PHP:

static __getStatic (name)

Similar to __get(), but it is used on Class instead of instance.

static __setStatic(name, value)

Similar to _ _set(), but used in Class instead of instance.

Why is magic method X not supported?

They are either unnecessary or impractical:

__construct() is not needed, Javascript already has a constructor.

__destruct(): There is no hook mechanism for object destruction in Javascript.

__call(): Contrary to PHP, methods are like attributes in Javascript, first obtained through __get(). To implement __call(), you simply return a function from get().

__callStatic(): Similar to __call(), but with __getStatic().

__sleep(), __wakeup(): Javascript does not have built-in serialization and deserialization. You can use JSON.stringify() and JSON.parse(), but they don’t have a mechanism to trigger any methods automatically.

__toString() has a corresponding toString() in Javascript

__invoke(): If you try to call a non-function object, Javascript will throw an error, which will not avoid.

__set_state(): There is no analogue of var_export() in Javascript.

__clone(): Hook for built-in cloning functionality in Javascript.

__debugInfo(): Unable to hook into console.log() output.

Can I extend classes with magic methods?

Yes, to an extent:

class Bar extends Foo {}
 // Or, if the class Bar itself contains magic methods:
 const Bar = magicMethods(class Bar extends Foo {
   //...
 })

But unfortunately, you cannot access properties in the parent class from the child class:

const Foo = magicMethods(  class Foo {
   __get() {
     return this. bar()
   }
 })
 class Bar extends Foo {
   bar() {
     return & # 39; value & # 39;
   }
 }
 // This *doesn't* call B's bar() method, but instead throws a TypeError:
 (new Bar).something