AG Coding

تالت طريقة وهي Deleted The Property Through A Proxy Object ايه هو ال proxy الأول A proxy is a way to insert some middle logic between an object’s common operations, like getting, setting, defining, and, deleting properties. حلو ؟ ال Proxy بيأخد اتنين parameters target: The object from where we want to create a proxy. handler: An object containing the middle logic for the operations. يعني ببساطة بتديلها الobject وتديلها ال logic اللي عاوز تطبقه جوا ال handler احنا بنعرف methodes لأي operations وبنسميها traps ليه بقي ؟ because they intercept the original operation and perform a custom change والنتيجة هتكون ان constructor هي return a Proxy object واللي هيكون identical لل target بس with the added middle logic تعال نبص ع مثال ؟ const user = { name : "zezo", age: 24, }; const handler = { get(target, property) { return user's ${property} is ${target[property]}; }, }; const userProxy = new Proxy(user, handler); console.log(userProxy.name); // user's breed is zezo console.log(userProxy.age); // user's age is 24 في المثل دا ال handler عمل modifies لل getting operation عشان ت return a custom value طب لو عاوز أ modifie ال Deleting operation ؟ const handler = { deleteProperty(target, property) { console.log(Deleting property: ${property}); }, }; هتحط دي جوا ال handler ف لو جيت const userProxy = new Proxy(user, handler); delete userProxy.name; // Deleting property: name هتلاقي دا ال output ولو جيت ت console.log(userProxy) // { name : "zezo", age: 24,}; متمسحتش ! عشان إحنا ببساطة بدلنا الdelete operator’s default behavior بcustom behavior اي اللي ييجي يلعب دور مهم هنا ؟ بقي Reflect اي ال reflect دي؟ Reflect is a global object with a collection of all the internal methods of an object. Its methods can be used as normal operations anywhere, but it’s meant to be used inside a proxy. بص هنستفيد من Reflect ازاي ف مثالنا const handler = { deleteProperty(target, property) { console.log(Deleting property: ${property}); return Reflect.deleteProperty(target, property); }, }; const userProxy = new Proxy(user, handler); delete userProxy.name; // Deleting property: name في حاجة مهمة هنا لازم أنوه ليها ؟ في بعض ال built in objects زي Math, Date, and JSON وغيرهم مقدرش أ delete منهم عشان ببساطة هما “non-configurable” object properties يعني مينفعش أعملهم reassign or delete