ES6 proxy for scala-style _.x.y function

script.js

class Access {
  constructor(path = []) {
    this.path = path;
  }
  
  // Proxy
  get(target, prop) {
    console.log("Packing", prop);
    return new Proxy(target, new Access([...this.path, o => o[prop]]));
  }
  apply(target, thisArg, args) {
    // Still packing
    if (args.length === 0) {  // _.a()
      return new Proxy(target, new Access([...this.path,
        function(o) { return o.apply(this.thisArg) }]));
    } else if (args[0] === _) { // _.a(_) called with rest of the arguments
      return new Proxy(target, new Access([...this.path,
        function(o) { return o.apply(this.thisArg, this.arguments) }]));
    }
    // Accessing
    this.arguments = args.slice(1);
    this.thisArg = thisArg;
    return this.path.reduce((o, step) => step.call(this, o), args[0]);
  }
}

let _ = new Proxy(o => o, new Access());

// Can now use (only for simple cases):
// array.map(_.prop1.prop2)
// array.map(_.func1().prop)
// array.map(_.func2(_).prop) (func2 will receive the other callback arguments: index, array)