Question

我目前的功能大约可以运行200次。

功能如下：

function GetB(av,bol){
var bxes=[
["11","12","13","21","22","23","31","32","33"],
["14","15","16","24","25","26","34","35","36"],
["17","18","19","27","28","29","37","38","39"],
["41","42","43","51","52","53","61","62","63"],
["44","45","46","54","55","56","64","65","66"],
["47","48","49","57","58","59","67","68","69"],
["71","72","73","81","82","83","91","92","93"],
["74","75","76","84","85","86","94","95","96"],
["77","78","79","87","88","89","97","98","99"]
];

//code
}

我的第一个问题是这个数组正在减慢一切，因为我认为每次数组bxes（或类似的东西）都会重写

此bxes数组永远不会被修改，我不介意将其设为全局数据。

我是否需要担心重写的事情？（或浏览器保持跟踪它是否曾被修改过，如果不是，它将不会重写它）

Answer 1

为什么不会你将它移到函数之外？（为什么冒风险导致性能问题？）

它不一定必须是“全局的” - 只是在函数的父作用域中 - 但函数和bxes以及其他代码都可以存在于父函数或闭包中...... < / p>

(function(){
  var bxes = [...];
  window.GetB = function(av,bol){...};
})();

Answer 2

简单的基准测试显示了答案。使用您编写的函数声明，5,000,000次调用需要12.739秒。将数组定义移到函数外部，同一个循环只消耗0.169。

请记住，这将根据JavaScript引擎 - 以及浏览器 - 的使用情况而有所不同。

重变量应该超出函数吗？

2 个答案: