isbound.js

Function.prototype.isBound = function() {
  return !this.prototype;
};

// Imaginary DOM library
var DOM = {};

// This function accepts a function as it's second argument,
// what happens when its a bound function? I'd like write the
// API in a way that is friendly to both types of function

DOM.each = function( elems, callbackFn ) {
  var elem, length, k;

  length = elems.length;
  k = -1;

  while ( ++k < length ) {
    elem = elems[k];

    if ( callbackFn.isBound() ) {
      callbackFn( k, elem );
    } else {
      callbackFn.call( elem, k, elem );
    }
  }
}

let nodes = document.querySelectorAll("body");

DOM.each( nodes, function( index ) {
  console.log(index, this);
});


function ListOfNodes( selector ) {
  let nodes = document.querySelectorAll( selector );

  // I don't want to return a NodeList, I'm
  // making my own API - WOO!

  DOM.each( nodes, index => {

    // |this| is the constructed instance
    this[ index ] = nodes[ index ];

  });

  this.length = nodes.length;
}

// I might make my own API for
// manipulating my ListOfNodes
// ListOfNodes.prototype.foo...


var list = new ListOfNodes("body");


function orig() {
  console.log(this);
}

orig.prototype = {};

var bound = orig.bind({});

bound.isBound();