How to set up javascript/jquery code for whole site or one page or some of both?

Question

Can someone explain this to me. I have 1 js file on my site, using mainly jQuery, all my js code uses elements that are on all pages, EXCEPT for 1 js code that targets an element that is only on one page.

So when I go to that one page, I get no JavaScript errors, however when I go to any other page it gives me a $..Undefined error for that element. I am using a .offset().top code for that element. I'm assuming that's because if you only target an element that's on one page I should just include a script on that page alone and not put it in my js file??? Does that include all jquery functions or just something specific to using .offset() and/or others? Is my assumption correct?

Before executing any action on the element, check if it exists : http://stackoverflow.com/questions/4592493/jquery-check-if-element-exists — Bassem, Jun 27 '13 at 17:37

score 1 · Accepted Answer · answered Jun 27 '13 at 17:37

1

Just put a quick check for that element in your JS file. Example, the element only on one page:

<span id="coolSpan">span stuff</span>

JS:

if ($("#coolSpan").length) {
    //element exists, bind the handler
    $("#coolSpan").click(function() {
        console.log("I exist!");
    });
}

answered Jun 27 '13 at 17:37

tymeJV

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If the element doesn't exist, your code should quietly do nothing anyway. `.offset().top`, however, will throw an error, because `$('not-an-element').offset()` returns `null`. – Blazemonger Jun 27 '13 at 17:37
It won't do anything, if it doesn't exist, it'll skip over this, yes? – tymeJV Jun 27 '13 at 17:38
It will do nothing if the element doesn't exist for event binding - think about when people forget to wrap their event binding code inside a document.ready function - no errors get thrown – wirey00 Jun 27 '13 at 17:45

score 1 · Answer 2 · answered Jun 27 '13 at 17:39

What I like to do is write my js pages like so:

var initMyFunction = function(){
     *code for initMyFunction*
};

var initMyOtherFunction = function(){
     *code for initMyOtherFunction*
};

And then in my mark up I can call which function I want to run on that page, so long as I call it after I call my script.

<!-- Scripts -->
<script src="js/main.js"></script>

<!-- Inits -->
<script>initMyFunction();</script>

It has the benefit of only running the code you need ran on that page, instead of running all your js on every page.

score 1 · Answer 3 · answered Jun 27 '13 at 17:42

If you are trying to access a function of an element that is not there, you will get an error regardless of the function you are using.

Solutions:

Like you said, you can put the specific code in a separate .js file and include that file only in the appropriate HTML page.
You could check for the element's existence and only then proceed with manipulating it. E.g.:

    var elem = document.getElementById("mySpecialElement");  
    if (elem) {  
        /* Element exists, it is safe to manipulate it */  
        $(elem).offset()...  
    }

score 0 · Answer 4 · edited May 23 '17 at 12:05

0

As you suggested, you could put it in a <script> tag in that page, however you could also simply check if the element exists before attempting to perform your operation.

edited May 23 '17 at 12:05

Community

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answered Jun 27 '13 at 17:37

J David Smith

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How to set up javascript/jquery code for whole site or one page or some of both?

4 Answers4