#Benalu

Better ES6 Proxy API for interception

Tired of complicated ES6 Proxy class API to do simple interception? Benalu is your friend

About

The purpose of Benalu is provide a simple API to do interception in JavaScript. Benalu also useful for IOC container library that hasn't support for interception

Installation

npm install benalu

How To Use It

Using benalu is very simple. You start building your proxy by using Benalu builder

var Benalu = require('benalu');

//declare the class
class MyObject(){
    getNumber() {
        return 700;
    }
}

//create instance
var myObject = new MyObject();
     
//make a proxy   
var proxy = Benalu.fromInstance(myObject)
    .addInterception(function(i) {
        //filter the invocation
        if(i.memberName == "getNumber"){
            //call the real method
            let result = i.proceed();
            //return different value
            return 300;
        }
    })
    .build();
    
var numResult = proxy.getNumber();
//numResult become 300 vs 700

Interception & Invocation

Interception in Benalu simply a callback function with single parameter of Invocation. Invocation consist of 3 important members:

1. memberName name of current invoked method or getter. Usefull when you only want to intercept specific method or getter of the class

2. memberType type of currently invoked member the vlaue could bemethod or getter

3. parameters arguments passed to the invoked method. Usefull when you want to get information of the arguments passed to the method.

4. proceed() method to proceed current invocation. This method will invoke the method of the real object.

Multiple Interception

Benalu also support multiple interception.

var Benalu = require('benalu');

class MyObject(){
    getNumber() {
        console.log("The real method called")
        return 700;
    }
}

var myObject = new MyObject();
     
var proxy = Benalu.fromInstance(myObject)
    .addInterception(function(i) {
        if(i.methodName == "getNumber"){
            console.log("First interceptor before proceed");
            let result = i.proceed();
            console.log("First interceptor after proceed");
            return result + 300
        }
    })
    .addInterception(function(i) {
        if(i.methodName == "getNumber"){
            console.log("Second interceptor before proceed");
            let result = i.proceed();
            console.log("Second interceptor after proceed");
            return 300
        }
    })
    .build();
    
var numResult = proxy.getNumber();
//numResult = 600

Above code will write log in the console like below:

First interceptor before proceed
Second interceptor before proceed
The real method called
Second interceptor after proceed
First interceptor after proceed