Question

40

Javascript Try-Catch Performance Vs. Error Checking Code

rated 0 times [ 41] [ 1] / answers: 1 / hits: 18853 / 14 Years ago, sat, july 10, 2010, 12:00:00

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

For example..

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;

    }

}

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

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jeffery

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1 Year ago

answered 14 Years ago raveno · Accepted Answer

"Programs must be written for people
to read, and only incidentally for
machines to execute."

Abelson & Sussman, SICP, preface to the first edition

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

Avoid try-catch in performance-critical functions, and loops

Anywhere else they won't do much harm. Use them wisely, use them when they make sense.

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))

can be written as

if (projectPhaseId != null)

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

I would bet this works as expected:

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



}

How cool is that? :)