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Asked: 2026-06-13T06:26:10+00:00

I am reviewing some code in our web site until I came to this

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I am reviewing some code in our web site until I came to this one 

<script>
    (function (a) {
        _q = function () { return a; };
        $ = function (f) { typeof f === 'function' && a.push(arguments); return $; };
        jQuery = $.ready = $;
    }([]));
</script>

And then followed by bunch of plugins including jQuery.
I just don’t get what it means, I want to know how it works so I would be able to manipulate the code. Can anyone explain the code line by line?

Edit

So sorry for the bad codes. I was also wandering of its use that’s why I ask it here. Anyway this is the whole code inside the head tag. 

<head>
    <meta charset="utf-8">
    @foreach (string domain in
    ViewBag.Prefetches is string[] ? ViewBag.Prefetches : new string[] { })
    {
        @Html.Prefetch(domain)    
    }
    <title>
        @{@ViewBag.SiteName
            if (ViewBag.Title != null)
            {  @ViewBag.SiteDelimiter @ViewBag.Title } 
        }
    </title>

    <meta name="description" content="">
    <meta name="author" content="">
    <meta http-equiv="imagetoolbar" content="false">

    <link href="@Url.ContentArea("~/css/global/normalize.css")" rel="stylesheet" />

    @foreach (string stylesheet in
    ViewBag.Stylesheets is string[] ? ViewBag.Stylesheets : new string[] { @"style.css" })
    { 
        <link href="@Url.ContentArea("~/css/" + stylesheet)" rel="stylesheet" />
    }

    @RenderSection("CustomCss", required: false)

    <link href="@Url.ContentArea("~/css/global/helpers.css")" rel="stylesheet" />
    <link href="@Url.ContentArea("~/css/global/media.css")" rel="stylesheet" />

    <script src="@Url.ContentArea("~/js/global/modernizr-2.5.3.min.js")"></script>

    <script>
        (function (a) {
            _q = function () { return a; };
            $ = function (f) { typeof f === 'function' && a.push(arguments); return $; };
            jQuery = $.ready = $;
        }([]));
    </script>

    @RenderSection("OverrideJs", required: false)
</head>
<script src="//ajax.googleapis.com/ajax/libs/jquery/1.7.2/jquery.min.js"></script>
<script>window.jQuery || document.write('<script src="@Url.ContentArea("~/js/global/jquery-1.7.2.min.js")"><\/script>');</script>
@foreach (string script in
    ViewBag.Scripts is string[] ? ViewBag.Scripts : new string[] { })
{ 
    <script src="@script"></script>
}
<script>
    Modernizr.load({
        test: window.JSON,
        nope: '@Url.Content("~/Scripts/Polyfills/json.polyfill.js")'
    });

    (function (i, s, q, l) {
        for (q = window._q(), l = q.length; i < l;) {
            $.apply(this, s.call(q[i++]));
        }
    }(0, Array.prototype.slice));

</script>
<!--[if lt IE 7 ]>
  <script src="//ajax.googleapis.com/ajax/libs/chrome-frame/1.0.2/CFInstall.min.js"></script>
  <script>window.attachEvent("onload",function(){CFInstall.check({mode:"overlay"})})</script>
<![endif]-->

I can’t provide a link because these codes were used in specific pages where you have to be logged in.
Anyway thanks for the help.

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1 Answer

  1. Editorial Team

    Short answer: It logs if jQuery’s been loaded

    Long answer: It looks like all it does is add a variable “jQuery” if it’s loaded, after adding to it a function _q that returns an array of arguments (which is an array-like variable that exist in all functions’ execution contexts, thanks Fabrício Matté). As far as I can tell since no arguments are sent into the function, all it’ll do is log the scope it’s been called from.

    It looks like the “jQuery” variable is accessed a bit further down, and if not set it loads jQuery. But I don’t think it could be accessed down there anyways since I don’t see the variable globally declared anywhere.

    What it’s used for is that it first tries to load jQuery from Google’s hosting. If that fails it loads jQuery locally.

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