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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