uncaught referenceerror $ is not defined error message, I don't know what caused this. please take a look [closed]

<script src="http://code.jquery.com/jquery.js" type="text/javascript"></script>

    $("#profile-picture").click(function () {
        alert("OUCHHHH!! IT HURTS!!!");
    });


    $("#show-button").click(function () {
        $(this).hide("fast");
        $("#basketball-hidden-content").css("display", "block");
        $("#hide-button").show("fast");
    });


    $("#hide-button").click(function () {
        $(this).hide("fast");
        $("#basketball-hidden-content").css("display", "none");
        $("#show-button").show("fast");
    });


    $("#Instagram").click(function () {
        $("#Instagram-link").fadeTo("slow", 1);
    });


    $("#Youtube").click(function () {
        $("#Youtube-link").fadeTo("slow", 1);
    });


    $("#WhatsApp").click(function () {
        $("#WhatsApp-link").fadeTo("slow", 1);
    });


    $("#Line").click(function () {
        $("#Line-link").fadeTo("slow", 1);
    });

</script>`

I uploaded my first personal website on GitHub recently, but I can't seem the get the jquery to work properly. I put a text that's supposed to show content if I press it, but it's not working. My friend debugged it and get the error message like the one on the title. I've found out that network connectivity might cause this to happen, but my device is connected to the internet. Can somebody help me with this problem??