Function extend

tests/qunit-2.9.2.js:224–236

(a, b, undefOnly)

  }

  function extend(a, b, undefOnly) {
  	for (var prop in b) {
  		if (hasOwn.call(b, prop)) {
  			if (b[prop] === undefined) {
  				delete a[prop];
  			} else if (!(undefOnly && typeof a[prop] !== "undefined")) {
  				a[prop] = b[prop];
  			}
  		}
  	}

  	return a;
  }

  function objectType(obj) {
  	if (typeof obj === "undefined") {