Want to load javascript only on mobile devices [duplicate]

Question

I want to load a carousel named "slick" only on mobile device. But the error comes [SyntaxError: unterminated string literal] in the line (document.write(""); Please help me out in solving the issue to load js only on mobile device or suggest another idea to achieve this.

Below is the bootstrap HTML code.

<!DOCTYPE html>
<html ng-app="gemStore">
    <head>
        <title></title>
        <link rel="stylesheet" href="http://maxcdn.bootstrapcdn.com/bootstrap/3.3.5/css/bootstrap.min.css">
        <link rel="stylesheet" type="text/css" href="slick/slick.css"/>
        <link rel="stylesheet" type="text/css" href="slick/slick-theme.css"/>
    </head>
    <body>
        <div class="container" aria-live="polite">
            <div class="row multiple-items">
                <div class="col-sm-2 col-xs-4">
                    <img src="img1.png">
                </div>
                <div class="col-sm-2 col-xs-4">
                    <img src="img2.png">
                </div>
                <div class="col-sm-2 col-xs-4">
                    <img src="img3.png">
                </div>
                <div class="col-sm-2 col-xs-4">
                    <img src="img1.png">
                </div>
                <div class="col-sm-2 col-xs-4">
                    <img src="img2.png">
                </div>
                <div class="col-sm-2 col-xs-4">
                    <img src="img3.png">
                </div>
            </div>

        </div>
        <script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.3/jquery.min.js"></script>
        <!-- Latest compiled JavaScript -->
        <script src="http://maxcdn.bootstrapcdn.com/bootstrap/3.3.5/js/bootstrap.min.js"></script>
        <script type="text/javascript" src="//code.jquery.com/jquery-migrate-1.2.1.min.js"></script>

        <script type="text/javascript">
            if (screen && screen.width < 480){
    document.write("<script type='text/javascript' src='slick/slick.min.js'></script>");
        }
    </script>

    <script type="text/javascript">

                if ($(window).width() < 400) {

        $(document).ready(function(){

        $('.multiple-items').slick({

        infinite: true,
                slidesToShow: 3,
                slidesToScroll: 3
        });
        });
        }

    </script>


</body>
</html>

@Quentin Please don't close a question as a duplicate of a question that's closed as a duplicate. — Bill the Lizard
– Bill the Lizard, Commented Aug 10, 2015 at 12:12
@BilltheLizard — I was a bit dubious about the other two questions being true duplicates of each other, so I went with the one that seemed a closer fit. I've opened a discussion on meta. — Quentin
– Quentin, Commented Aug 10, 2015 at 12:52

Reece Kenney · Accepted Answer · 2015-08-10 11:04:28Z

0

Here is a little function you can use to return true or false depending on whether the user is on a mobile device:

function is_mobile() {
    var agents = ['android', 'webos', 'iphone', 'ipad', 'blackberry'];
    for(i in agents) {
        if(navigator.userAgent.match('/'+agents[i]+'/i')) {
            return true;
        }
    }
    return false;
}

From there you can simply execute some code like so:

if (is_mobile()) {

    //Mobile device detected. Do some stuff...
}

answered Aug 10, 2015 at 11:04

Reece Kenney

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1 Comment

Quentin Over a year ago

This doesn't address the problem described in the question. You've rewritten the mobile detection code without fixing the broken script loading code.

Dan-Levi Tømta · Accepted Answer · 2015-08-10 11:37:54Z

You can check navigator.userAgent and see if it is a mobile devide.

Here is an example

HTML

<div class="navbar-wrapper">
  <div class="container">
    <nav class="navbar navbar-inverse navbar-static-top">
      <div class="container">
        <div class="navbar-header">
            <span class="sr-only">Toggle navigation</span>
            <span class="icon-bar"></span>
            <span class="icon-bar"></span>
            <span class="icon-bar"></span>
          </button>
          <a class="navbar-brand" href="#">Carousel showing on mobile devices</a>
        </div>
      </div>
    </nav>
  </div>
</div>
<div id="myCarousel" class="carousel slide" data-ride="carousel" style="display:none;">
  <!-- Indicators -->
  <ol class="carousel-indicators">
    <li data-target="#myCarousel" data-slide-to="0" class="active"></li>
    <li data-target="#myCarousel" data-slide-to="1" class=""></li>
    <li data-target="#myCarousel" data-slide-to="2" class=""></li>
  </ol>
  <div class="carousel-inner" role="listbox">
    <div class="item active">
      <img class="first-slide" src="data:image/gif;base64,R0lGODlhAQABAIAAAHd3dwAAACH5BAAAAAAALAAAAAABAAEAAAICRAEAOw==" alt="First slide">
      <div class="container">
        <div class="carousel-caption">
          <h1>Example headline.</h1>
          <p>Note: If you're viewing this page via a <code>file://</code> URL, the "next" and "previous" Glyphicon buttons on the left and right might not load/display properly due to web browser security rules.</p>
          <p><a class="btn btn-lg btn-primary" href="#" role="button">Sign up today</a></p>
        </div>
      </div>
    </div>
    <div class="item">
      <img class="second-slide" src="data:image/gif;base64,R0lGODlhAQABAIAAAHd3dwAAACH5BAAAAAAALAAAAAABAAEAAAICRAEAOw==" alt="Second slide">
      <div class="container">
        <div class="carousel-caption">
          <h1>Another example headline.</h1>
          <p>Cras justo odio, dapibus ac facilisis in, egestas eget quam. Donec id elit non mi porta gravida at eget metus. Nullam id dolor id nibh ultricies vehicula ut id elit.</p>
          <p><a class="btn btn-lg btn-primary" href="#" role="button">Learn more</a></p>
        </div>
      </div>
    </div>
    <div class="item">
      <img class="third-slide" src="data:image/gif;base64,R0lGODlhAQABAIAAAHd3dwAAACH5BAAAAAAALAAAAAABAAEAAAICRAEAOw==" alt="Third slide">
      <div class="container">
        <div class="carousel-caption">
          <h1>One more for good measure.</h1>
          <p>Cras justo odio, dapibus ac facilisis in, egestas eget quam. Donec id elit non mi porta gravida at eget metus. Nullam id dolor id nibh ultricies vehicula ut id elit.</p>
          <p><a class="btn btn-lg btn-primary" href="#" role="button">Browse gallery</a></p>
        </div>
      </div>
    </div>
  </div>
  <a class="left carousel-control" href="#myCarousel" role="button" data-slide="prev">
    <span class="glyphicon glyphicon-chevron-left" aria-hidden="true"></span>
    <span class="sr-only">Previous</span>
  </a>
  <a class="right carousel-control" href="#myCarousel" role="button" data-slide="next">
    <span class="glyphicon glyphicon-chevron-right" aria-hidden="true"></span>
    <span class="sr-only">Next</span>
  </a>
</div>

Take note of the id of the carousel myCarousel. It is initially hidden

display:none;

Now make a extensive function to check what kind of device that is browsing the page

Javascript

function isMobile() {
    // set the bool to be false initially
    var isMobile = false; 
    // Check if it is a mobile by testing the userAgent. If it is recognized set the isMobile bool to true
    if(/(android|bb\d+|meego).+mobile|avantgo|bada\/|blackberry|blazer|compal|elaine|fennec|hiptop|iemobile|ip(hone|od)|ipad|iris|kindle|Android|Silk|lge |maemo|midp|mmp|netfront|opera m(ob|in)i|palm( os)?|phone|p(ixi|re)\/|plucker|pocket|psp|series(4|6)0|symbian|treo|up\.(browser|link)|vodafone|wap|windows (ce|phone)|xda|xiino/i.test(navigator.userAgent) 
    || /1207|6310|6590|3gso|4thp|50[1-6]i|770s|802s|a wa|abac|ac(er|oo|s\-)|ai(ko|rn)|al(av|ca|co)|amoi|an(ex|ny|yw)|aptu|ar(ch|go)|as(te|us)|attw|au(di|\-m|r |s )|avan|be(ck|ll|nq)|bi(lb|rd)|bl(ac|az)|br(e|v)w|bumb|bw\-(n|u)|c55\/|capi|ccwa|cdm\-|cell|chtm|cldc|cmd\-|co(mp|nd)|craw|da(it|ll|ng)|dbte|dc\-s|devi|dica|dmob|do(c|p)o|ds(12|\-d)|el(49|ai)|em(l2|ul)|er(ic|k0)|esl8|ez([4-7]0|os|wa|ze)|fetc|fly(\-|_)|g1 u|g560|gene|gf\-5|g\-mo|go(\.w|od)|gr(ad|un)|haie|hcit|hd\-(m|p|t)|hei\-|hi(pt|ta)|hp( i|ip)|hs\-c|ht(c(\-| |_|a|g|p|s|t)|tp)|hu(aw|tc)|i\-(20|go|ma)|i230|iac( |\-|\/)|ibro|idea|ig01|ikom|im1k|inno|ipaq|iris|ja(t|v)a|jbro|jemu|jigs|kddi|keji|kgt( |\/)|klon|kpt |kwc\-|kyo(c|k)|le(no|xi)|lg( g|\/(k|l|u)|50|54|\-[a-w])|libw|lynx|m1\-w|m3ga|m50\/|ma(te|ui|xo)|mc(01|21|ca)|m\-cr|me(rc|ri)|mi(o8|oa|ts)|mmef|mo(01|02|bi|de|do|t(\-| |o|v)|zz)|mt(50|p1|v )|mwbp|mywa|n10[0-2]|n20[2-3]|n30(0|2)|n50(0|2|5)|n7(0(0|1)|10)|ne((c|m)\-|on|tf|wf|wg|wt)|nok(6|i)|nzph|o2im|op(ti|wv)|oran|owg1|p800|pan(a|d|t)|pdxg|pg(13|\-([1-8]|c))|phil|pire|pl(ay|uc)|pn\-2|po(ck|rt|se)|prox|psio|pt\-g|qa\-a|qc(07|12|21|32|60|\-[2-7]|i\-)|qtek|r380|r600|raks|rim9|ro(ve|zo)|s55\/|sa(ge|ma|mm|ms|ny|va)|sc(01|h\-|oo|p\-)|sdk\/|se(c(\-|0|1)|47|mc|nd|ri)|sgh\-|shar|sie(\-|m)|sk\-0|sl(45|id)|sm(al|ar|b3|it|t5)|so(ft|ny)|sp(01|h\-|v\-|v )|sy(01|mb)|t2(18|50)|t6(00|10|18)|ta(gt|lk)|tcl\-|tdg\-|tel(i|m)|tim\-|t\-mo|to(pl|sh)|ts(70|m\-|m3|m5)|tx\-9|up(\.b|g1|si)|utst|v400|v750|veri|vi(rg|te)|vk(40|5[0-3]|\-v)|vm40|voda|vulc|vx(52|53|60|61|70|80|81|83|85|98)|w3c(\-| )|webc|whit|wi(g |nc|nw)|wmlb|wonu|x700|yas\-|your|zeto|zte\-/i.test(navigator.userAgent.substr(0,4))) isMobile = true; //This is a mobile
    return isMobile
}

Now all you have to do is to check if the device is mobile, and if it is, show the carousel:

Javascript (jQuery)

$(function () {
    if (isMobile()) {
        $('#myCarousel').show();
    };
});

And here is a fiddle: http://jsfiddle.net/zLj5wuv5/1/

Edit:

To anser your question more directly, how to add javaScripts dynamically:

Javascript (jQuery)

$(function () {
    if (isMobile()) {
        $.getScript("slick/slick.min.js", function(){
            alert("Running slick.min.js");
        });
    };
});

function isMobile() {
    // set the bool to be false initially
    var isMobile = false; 
    // Check if it is a mobile by testing the userAgent. If it is recognized set the isMobile bool to true
    if(/(android|bb\d+|meego).+mobile|avantgo|bada\/|blackberry|blazer|compal|elaine|fennec|hiptop|iemobile|ip(hone|od)|ipad|iris|kindle|Android|Silk|lge |maemo|midp|mmp|netfront|opera m(ob|in)i|palm( os)?|phone|p(ixi|re)\/|plucker|pocket|psp|series(4|6)0|symbian|treo|up\.(browser|link)|vodafone|wap|windows (ce|phone)|xda|xiino/i.test(navigator.userAgent) 
    || /1207|6310|6590|3gso|4thp|50[1-6]i|770s|802s|a wa|abac|ac(er|oo|s\-)|ai(ko|rn)|al(av|ca|co)|amoi|an(ex|ny|yw)|aptu|ar(ch|go)|as(te|us)|attw|au(di|\-m|r |s )|avan|be(ck|ll|nq)|bi(lb|rd)|bl(ac|az)|br(e|v)w|bumb|bw\-(n|u)|c55\/|capi|ccwa|cdm\-|cell|chtm|cldc|cmd\-|co(mp|nd)|craw|da(it|ll|ng)|dbte|dc\-s|devi|dica|dmob|do(c|p)o|ds(12|\-d)|el(49|ai)|em(l2|ul)|er(ic|k0)|esl8|ez([4-7]0|os|wa|ze)|fetc|fly(\-|_)|g1 u|g560|gene|gf\-5|g\-mo|go(\.w|od)|gr(ad|un)|haie|hcit|hd\-(m|p|t)|hei\-|hi(pt|ta)|hp( i|ip)|hs\-c|ht(c(\-| |_|a|g|p|s|t)|tp)|hu(aw|tc)|i\-(20|go|ma)|i230|iac( |\-|\/)|ibro|idea|ig01|ikom|im1k|inno|ipaq|iris|ja(t|v)a|jbro|jemu|jigs|kddi|keji|kgt( |\/)|klon|kpt |kwc\-|kyo(c|k)|le(no|xi)|lg( g|\/(k|l|u)|50|54|\-[a-w])|libw|lynx|m1\-w|m3ga|m50\/|ma(te|ui|xo)|mc(01|21|ca)|m\-cr|me(rc|ri)|mi(o8|oa|ts)|mmef|mo(01|02|bi|de|do|t(\-| |o|v)|zz)|mt(50|p1|v )|mwbp|mywa|n10[0-2]|n20[2-3]|n30(0|2)|n50(0|2|5)|n7(0(0|1)|10)|ne((c|m)\-|on|tf|wf|wg|wt)|nok(6|i)|nzph|o2im|op(ti|wv)|oran|owg1|p800|pan(a|d|t)|pdxg|pg(13|\-([1-8]|c))|phil|pire|pl(ay|uc)|pn\-2|po(ck|rt|se)|prox|psio|pt\-g|qa\-a|qc(07|12|21|32|60|\-[2-7]|i\-)|qtek|r380|r600|raks|rim9|ro(ve|zo)|s55\/|sa(ge|ma|mm|ms|ny|va)|sc(01|h\-|oo|p\-)|sdk\/|se(c(\-|0|1)|47|mc|nd|ri)|sgh\-|shar|sie(\-|m)|sk\-0|sl(45|id)|sm(al|ar|b3|it|t5)|so(ft|ny)|sp(01|h\-|v\-|v )|sy(01|mb)|t2(18|50)|t6(00|10|18)|ta(gt|lk)|tcl\-|tdg\-|tel(i|m)|tim\-|t\-mo|to(pl|sh)|ts(70|m\-|m3|m5)|tx\-9|up(\.b|g1|si)|utst|v400|v750|veri|vi(rg|te)|vk(40|5[0-3]|\-v)|vm40|voda|vulc|vx(52|53|60|61|70|80|81|83|85|98)|w3c(\-| )|webc|whit|wi(g |nc|nw)|wmlb|wonu|x700|yas\-|your|zeto|zte\-/i.test(navigator.userAgent.substr(0,4))) isMobile = true; //This is a mobile
    return isMobile
}

This doesn't address the problem described in the question. You've rewritten the mobile detection code without fixing the broken script loading code.
I hope it will work. Is there any way to check the code on mobile device without any server configuration ? Thanks Friend !
Just open the fiddle url i provided above in my answer with both the computer and the mobile and see the difference.

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