constructor compatible with be calling as ordinary function

constructor.js

// check the prototype
function init(args){
  if (Object.getPrototypeOf(this) !== init.prototype) {
    // called without `new`
    return new init(args);
  }
  this.args = args;
}

// check the constructor
function construct(args){
  if (Object.getPrototypeOf(this).constructor !== construct) {
    // called without `new`
    return new construct(args);
  }
  this.args = args;
}