array_type_checking_performance.js

var iterations = 1000000;
var some_type = true;

function isArray(value) {
	return Object.prototype.toString.call(value) === '[object Array]';
};

var startTime = performance.now();
for (var i = 0; i < iterations; i++) {
	if (isArray(some_type)) {
  	
  }
}

var timeTaken = performance.now() - startTime;
console.log('isArray time: ' + Math.round(timeTaken));

function defined(arg) {
	return arg !== undefined && arg !== null;
}
startTime = performance.now();
for (var i = 0; i < iterations; i++) {
	if (!defined(some_type)) {
  	
  }
}

var timeTaken = performance.now() - startTime;
console.log('defined time: ' + Math.round(timeTaken));