Dependency injection

dependency-injection.js

var DI = function () {
  let _deps = {}
  
  this.dep = (name, func) => { _deps[name] = func }
  this.getDep = (name) => _deps[name]
}

DI.prototype.inject = function (fn) {
  let fnString = fn.toString().replace(/((\/\/.*$)|(\/\*[\s\S]*?\*\/))/mg, ''),
      paramNames = fnString.split('(')[1].split(')')[0].split(',').map(v => v.trim()),
      args = paramNames.map((x) => this.getDep(x))

  return () => fn.apply(null, args)
}

test.js

var di = new DI();
di.dep('dep1', function () { return 'this is dep1' })
di.dep('dep2', function () { return 'this is dep2' })
di.dep('dep3', function () { return 'this is dep3' })
di.dep('dep4', function () { return 'this is dep4' })

var myFunc = di.inject((dep3, dep1, dep2) => {
  return [ dep1(), dep2(), dep3() ].join(' -> ')
})

myFunc() // 'this is dep1 -> this is dep2 -> this is dep3'