README
ProxyMate
Introduction
This library provides a wrapper for ES6 Proxies that can be used to emulate protected class properties as well as provide data encapsulation.
Examples
class SimpleClass {
constructor() {
this.data = {
'propA': 'this is prop a',
'propB': 'this is prop b'
};
}
}
// Simple data encapsulation
let obj1 = proxy(new SimpleClass(), [], ['data']);
console.log(obj1.propA); // 'this is prop a'
console.log(obj1.data.propA); // 'this is prop a'
obj1.propA = 'prop a has changed';
console.log(obj1.propA); // 'prop a has changed'
console.log(obj1.data.propA); // 'prop a has changed'
// Data encapsulation with read-only members
let obj2 = proxy(new SimpleClass(), ['data'], ['data']);
console.log(obj2.propA); // 'this is prop a'
console.log(obj2.data.propA); // 'this is prop a'
obj2.propA = 'prop a is read-only'; // throws exception
console.log(obj2.propA); // 'this is prop a'
console.log(obj2.data.propA); // 'this is prop a'
// Complex example with a nested proxy
let obj3 = proxy(new SimpleClass(), ['data'], ['data']);
let obj4 = proxy(new SimpleClass(), [], ['data']);
obj3.nested = obj4;
console.log(obj3.propA); // 'this is prop a'
console.log(obj3.data.propA); // 'this is prop a'
console.log(obj3.nested.propA); // 'this is prop a'
console.log(obj3.nested.data.propA); // 'this is prop a'
obj3.propA = 'prop a is read-only'; // throws exception
obj3.nested.propA = 'prop a of the inner proxy can be modified';
console.log(obj3.nested.propA); // 'prop a of the inner proxy can be modified'
console.log(obj3.nested.data.propA); // 'prop a of the inner proxy can be modified'
Classes can also be proxied automatically in the constructor.
// Typically, value objects should not be modifiable once created
class ValueObject {
constructor(sourceData = {}) {
this.data = sourceData;
return proxy(this, ['data'], ['data']);
}
}
You don't have to use ES6 classes, either. Plain objects are ok too!
const getObj = () => ({
propA: 'this is prop a',
propB: 'this is prop b',
nested: {
propC: 'this is nested.propC',
},
});
// Make a pure value object by marking everything read-only
let obj4 = proxy(getObj(), '*');
obj4.propA = 'prop a is read-only'; // throws exception
obj4.propB = 'prop b is read-only'; // throws exception
obj4.nested.propC = 'even nested props are read-only'; // throws exception
License
MIT License. See LICENSE.md for the complete license text.