ES6 Decorators Example

decorators.js

// Demo on how to use ES6 decorators
// HOW TO RUN
// $ yarn add --dev babel-plugin-transform-decorators-legacy
// $ babel-node --plugins transform-decorators-legacy test.js
'use strict'

@meta({
    manufacturer: 'evolas'
})
class Data {
    @fluent
    set(key, value) {
        this[key] = value
    }

    show() {
        console.log(JSON.stringify(this))
    }

    toJSON() {
        var tmp = {};

        for (var key in this) {
            if (typeof this[key] !== 'function')
                tmp[key] = this[key];
        }

        return tmp;
    }
}

// target – The class that the decorator is used on.
// key – If using the decorator on a property, this is the name of the property.
// descriptor – Contains the properties value, enumerable, configurable, and writable for the property/function.
function fluent(target, name, descriptor) {
    const method = descriptor.value;

    descriptor.value = function(...args) {
        method.apply(this, args);
        return this;
    }
}

function meta(object) {
    return function(target) {
        Object.keys(object).forEach(
            key => target.prototype[key] = object[key]
        )
    }
}

var c = new Data()
c.set('pre', 1).set('post', 3)
c.show()