https://github.com/lodash/lodash/issues/821

demethodize.js

function demethodize(fn) {
  if (typeof fn === "function") {
    return Function.bind.bind(Function.call)(fn);
  }
  return null;
}

_.mixin((function() {
  return {
    demethodize: function(fn) {
      return _.bind(_.call, fn);
    }
  };
})());

function testDemethodize(input, fn) {
  var result = Array.isArray(input) ? input.map(fn) : fn.call(null, null, input);
  console.log('result', result);
}

testDemethodize(['a', 'b', 'c'], _.demethodize(String.prototype.toUpperCase));
testDemethodize(['a', 'b', 'c'], demethodize(String.prototype.toUpperCase));
testDemethodize({ a: 1 }, _.demethodize(Object.keys));