Javascript Try-Catch Performance Vs.检查代码时出错 [英] Javascript Try-Catch Performance Vs. Error Checking Code

问题描述

将代码放入try-catch块而不是执行各种错误检查会更快吗？

Would it be faster to just put code inside a try-catch block instead of performing various error checks?

例如..

function getProjectTask(projectTaskId) {
    if (YAHOO.lang.isUndefined(projectTaskId) || YAHOO.lang.isNull(projectTaskId) && !YAHOO.lang.isNumber(projectTaskId)) {
        return null;
    }

    var projectPhaseId, projectPhaseIndex, projectTaskIndex, projectPhases, projectPhase, projectTask;

    if (!YAHOO.lang.hasOwnProperty(projectTaskPhaseMap, projectTaskId)) {
        return null;
    }

    projectPhaseId = projectTaskPhaseMap[projectTaskId];

    if (YAHOO.lang.isUndefined(projectPhaseId) || YAHOO.lang.isNull(projectPhaseId) || !YAHOO.lang.hasOwnProperty(scheduleData.ProjectPhasesMap, projectPhaseId)) {
        return null;
    }

    projectPhaseIndex = scheduleData.ProjectPhasesMap[projectPhaseId];
    if (YAHOO.lang.isUndefined(projectPhaseIndex) || YAHOO.lang.isNull(projectPhaseIndex) || !YAHOO.lang.hasOwnProperty(scheduleData.ProjectPhases[projectPhaseIndex])) {
        return null;
    }
    projectPhase = scheduleData.ProjectPhases[projectPhaseIndex];

    if (!YAHOO.lang.hasOwnProperty(projectPhase.ProjectTasksMap, projectTaskId)) {
        return null;
    }

    projectTaskIndex = projectPhase.ProjectTasksMap[projectTaskId];

    if (YAHOO.lang.isUndefined(projectTaskIndex) || YAHOO.lang.isNull(projectTaskIndex)) {
        return null;
    }

    projectTask = scheduleData.ProjectTasks[projectTaskIndex];
}

VS

function getProjectTask(projectTaskId) {
    try {
        projectPhaseId = projectTaskPhaseMap[projectTaskId];
        projectPhaseIndex = scheduleData.ProjectPhasesMap[projectPhaseId];
        projectPhase = scheduleData.ProjectPhases[projectPhaseIndex];
        projectTaskIndex = projectPhase.ProjectTasksMap[projectTaskId];
        projectTask = scheduleData.ProjectTasks[projectTaskIndex];

    }
    catch (e) {
        return null;
    }
}

我希望我的问题有道理。我很乐意澄清。
谢谢！

I hope my question makes sense. I would be happy to clarify. Thank you!

推荐答案

必须为人们编写程序
可以阅读，只有偶然的
机器才能执行。

Abelson& Sussman，SICP，第一版序言

始终瞄准<​​strong>可读代码。要记住的关键是：

Always aim for readable code. The key thing to remember is:

避免性能关键函数中的try-catch和循环

在其他地方，他们不会造成太大伤害。明智地使用它们，谨慎使用它们。作为旁注，如果你想支持旧浏览器，他们可能没有试用。

Anywhere else they won't do much harm. Use them wisely, use them sparingly. As a side note if you want to support older browsers they may not have try-catch.

但是我看到你明显误用了一些函数进行错误检查。您可以在使用对象之前测试所需的对象和属性，而不是复杂的检查。并且：

But as I see you clearly misuse some functions for error checking. You can test for the desired objects and properties of objects right before you use them instead of complex checking. And:

if (YAHOO.lang.isUndefined(projectPhaseId) || YAHOO.lang.isNull(projectPhaseId))

可以写成

if (projectPhaseId != null)

例如...所以上面的例子可以即使没有尝试捕获也相当可读。你似乎滥用 YUI了。

for example... So the example above can be fairly readable even without try catches. You seem to misuse YUI a bit.

我敢打赌这可行符合预期：

function getProjectTask(projectTaskId) {

   var projectPhaseId    = projectTaskPhaseMap[projectTaskId],
       projectPhaseIndex = scheduleData.ProjectPhasesMap[projectPhaseId],
       projectPhase      = scheduleData.ProjectPhases[projectPhaseIndex];

  if (projectPhase == null) return null; // projectPhase would break the chain

  var projectTaskIndex  = projectPhase.ProjectTasksMap[projectTaskId],
      projectTask       = scheduleData.ProjectTasks[projectTaskIndex];

   return projectTask || null; // end of the dependency chain

}

酷如何是那个？ ：）

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