index.js

'use strict';

var isObject = require('is-extendable');

module.exports = function extend(o/*, objects*/) {
  if (!isObject(o)) { o = {}; }

  var len = arguments.length;
  for (var i = 1; i < len; i++) {
    var obj = arguments[i];

    if (isObject(obj)) {
      assign(o, obj);
    }
  }
  return o;
};

function assign(a, b) {
  for (var key in b) {
    if (hasOwn(b, key)) {
      a[key] = b[key];
    }
  }
}

/**
 * Returns true if the given `key` is an own property of `obj`.
 */

function hasOwn(obj, key) {
  return Object.prototype.hasOwnProperty.call(obj, key);
}