js函数性能对比的案例

/**
	 * 函数性能比较
	 * @param fns 要比较的函数数组
	 * @args 每个要比较函数在执行的时候传入的参数,可以是数组,或者 被调用后 返回数组类型
	 * @repeatCount 每个函数重复执行的次数,多次执行 拉开差距。默认值10000
	 * 
	 * @return [{runTime:执行repeatCount次总时间,repeatCount:重复执行次数,name:函数名称,chrome是函数名,IE由于不支持funciton.name,所以默认 fn+函数在fns中index}]
	 * */
	function proferencesCompare(fns, args, repeatCount) {
		var tmpArgs, tmpFns;
		var result = [];
		var starTime, endTime;
		var i = 0;
		var repeatCount = repeatCount || 10000;
		var isFunction = false;
		if(fns === undefined) {
			throw Error('Must have the compare funciton');
		}
 
		var typeName = typeof args;
 
		//检测传入的args是否能够返回array类型数据
		if(typeName === 'function') {
			tmpArgs = args();
			isFunction = true;
		}
 
		if(typeName === 'number') {
			tmpArgs = [];
			repeatCount = args;
		}
 
		//检测args 是否为 array
		if(Object.prototype.toString.call(tmpArgs) !== '[object Array]') {
			throw Error('The test args is must a array or a function which return the array');
		}
 
		var len = fns.length;
		for(; i < len; i++) {
			var fnName = fns[i].name || "fn" + i;
			starTime = Date.now();
			console.time(fnName);
			for(var j = 0; j < repeatCount; j++) {
				if(isFunction && (i !== 0 || j !== 0)) {
					//如果args是函数,并且循环是第一次进入,则不需要再执行一次。前面做args检测时已经执行过一次
					tmpArgs = args();
				}
				fns[i].apply(this, tmpArgs);
			}
			console.timeEnd(fnName);
			endTime = Date.now();
			result.push({ runTime: endTime - starTime, repeatCount: repeatCount, name: fnName });
		}
		return result;
	}

var fn1 = function() {
		var a;
		return !a;
	}
 
var fn2 = function() {
		var a;
		return a === undefined;
	}
 
var fn3 = function() {
		var a;
		return a == undefined;
	}
 
var result = proferencesCompare([fn1, fn2, fn3, fn3, fn2, fn1], 1000000000);

int[] array = { 15,20,10,3,5};
Stopwatch sw = new Stopwatch();
sw.Start();

for (int i = 0; i < array.Length - 1; i++) {
  for (int j = i + 1; j < array.Length; j++) {
    if (array[i] > array[j]) {

      int temp = array[i];
      array[i] = array[j];
      array[j] = temp;
    }
  }
}
sw.Stop();
Console.WriteLine(sw.Elapsed);