decorator-wrap

A ES6 decorator for wrapping classes or class methods with you own custom code. You can also edit the parameters!

With it you can easily make:

• logger functions
• edit the input parameters to a method
• edit the output from a method
• do something extra with the result (ie write to file)
• skip calling the method
• do what you want...

Please see tests for more examples

Should also work in frontend code if you use babel with es7.decorators enabled.

Install

$ npm install --save decorator-wrap

Usage

Make a function that have 4 parameters:

| parameters | description                                                                 |
|------------|-----------------------------------------------------------------------------| 
| callback   | The actual method/class. REMEBER TO INVOKE THIS METHOD AND RETURN THE VALUE |
| args       | The arguments passed into the original method/class                                  |
| name       | The method name of the method/class that is invoked                         |
| type       | The object type where the decorator is placed (class or function)           |

Here is an example:

// ES2016 style
import {wrap} from 'decorator-wrap'

// CommonJS style
let wrap = require('decorator-wrap').wrap;

var log = (callback, args, name, type) => {
  console.log('Starting  ', type, name);
  var result = callback();
  console.log('Ended: ', name);
  return result;
};

@wrap(log)
class SuperNiceClass {
    constructor(){
        //some business here.... 
        console.log('hello from class');
        //some business here.... 
    }
    @wrap(log)
    bar(a,b) {
        //some business here.... 
        console.log('hello from bar method');
        //some business here.... 
    }
}

new SuperNiceClass().bar(1,2);

Result

Starting class SuperNiceClass
hello from class
Ended: SuperNiceClass
Starting function bar
hello from bar method
Ended: bar

For more examples see test/wrap.test.js

Plugins

You can easily make plugins to this module by simply doing this

log.js

// ------------ log.js -------------
var wrap = require('decorator-wrap').wrap;

var log = function (callback, args, name, type){
  console.log('Starting  ', type, name);
  var result = callback();
  console.log('Ended: ', name);
  return result;
};

module.exports = function(target, key, descriptor) {
    return wrap(log)(target, key, descriptor);
}

FooBar.js

// ------------- FooBar.js ------------
var require('./log');

@log
class FooBar{
    @log
    foo() {
        //some business here....
    }

    @log
    bar(){
        //some business here....
    }
}

Available plugins

• decorator-promise - Transforms your classmethods to promises
• decorator-performance - A ES6 decorator for logging out performance.

Note

You need to run babel with the option 'es7.decorators' enabled.

License

MIT © Christian Martin