Uncaught ReferenceError: (function) not defined at HTMLButtonElement.onclick

Question 1

Uncaught ReferenceError: (function) not defined at HTMLButtonElement.onclick

javascript html referenceerror

AlxTay · Jan 8, 2017 · Viewed 46.1k times · Source

Answer

Answer

You have a syntax error in your script and thus the js fails.

You have to separate arrays values with commas, i.e. change

//Car Colour Image
var colourImages =
[
    "../IMAGES/windowsred.jpg"
    "../IMAGES/bmwblue.jpg"
    "../IMAGES/bmwgreen.jpg"
];

//Car Window Image
var windowImages =
[
    "../IMAGES/bmwwindowred"
    "../IMAGESbmwwindowblue"
    "../IMAGES/bmwwindowgreen"
];

to

//Car Colour Image
var colourImages =
[
    "../IMAGES/windowsred.jpg",
    "../IMAGES/bmwblue.jpg",
    "../IMAGES/bmwgreen.jpg"
];

//Car Window Image
var windowImages =
[
    "../IMAGES/bmwwindowred",
    "../IMAGESbmwwindowblue",
    "../IMAGES/bmwwindowgreen"
];

Question 2

The following functions, onColourChange and onWindowChange, should cycle through images on button click. Instead, I get both:

Uncaught ReferenceError: onColourChange is not defined at HTMLButtonElement.onclick

and

Uncaught ReferenceError: onWindowChange is not defined at HTMLButtonElement.onclick

HTML:

    <head>
    <title>TravelSmart</title>
    <link rel="stylesheet" type="text/css" href="../CSS/style.css">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <link rel="icon" href="../IMAGES/TravelSmart.ico">
    <script type="text/javascript" language="javascript" src="../JS/bmwcustom.js"></script>
</head>

<body>
<div id=wrapper> 
    <header>
        <img class="logo" src="../IMAGES/TravelSmart.png">
    </header>

    <nav>   
        <ul class="navbar">
            <li><a class="active" href="../HTML/index.htm">Home</a></li>
            <li><a href="../HTML/News.html">News</a></li>
            <li><a href="../HTML/Products.html">Products</a></li>
            <li><a href="../HTML/OpeningHours.html">Opening Hours</a></li>
            <li><a href="../HTML/Location.html">Location</a></li>
            <li><a href="../HTML/Offers.html">Offers</a></li>
        </ul>
    </nav>

<main>
    <div class="customcontainer">
        <div class="colour">
            <img id="colour-image" src="../IMAGES/o"/>
            <button class="left-button" onclick="onColourChange(+1)">&laquo;</button>
            <button class="right-button" onclick="onColourChange(+1)">&raquo;</button>
        </div>

        <div class="windows">
        <img id="windows-image" src="../IMAGES/x"/>
        <button class="left-button" onclick="onWindowChange(+1)">&laquo;</button>
        <button class="right-button" onclick="onWindowChange(+1)">&raquo;</button>
        </div>
    </div>

    <input id="selector-box" type="text" value="h: 0 | t: 0" readonly />

</main>


</div>
</body>

JavaScript:

//Car Colour Image
var colourImages =
[
    "../IMAGES/windowsred.jpg"
    "../IMAGES/bmwblue.jpg"
    "../IMAGES/bmwgreen.jpg"
];

//Car Window Image
var windowImages =
[
    "../IMAGES/bmwwindowred"
    "../IMAGESbmwwindowblue"
    "../IMAGES/bmwwindowgreen"
];

//Component Index
var colourIndex, windowIndex;

//Default to 0
colourIndex = windowIndex = 0;

//Current Component
var colourImage, windowImage;

//On page load call:
window.onload = function()
{
    //Element for each component
    colourImage = document.getElementById("colour-image");
    windowImage = document.getElementById("windows-image");

    //Set initial
    onCarChanged();
}

//Updated Selector Box with Current Selecton
function updateSelectorBox()
{
    //Get the element to be changed
    var selectorBox = document.getElementById("selector-box");

    //Set the value to 0
    selectorBox.value = "";

    //Append each index to string
    selectorBox.value += ("Colour: " + colourIndex + " | ");
    selectorBox.value += ("Colour: " + windowIndex);
}

//Call when colour is changed
function onColourChange(offset)
{
    //Find the index which is offset from the current head index by the given offset.
    var offsetIndex = (colourIndex + offset);

    //If negative set index to last image
    if(offsetIndex < 0)
        colourIndex = colourImages.length + offset;

    //Otherwise add offset and modulo by the length to wrap around the values.
    else
        colourIndex = (colourIndex + offset) % colourImages.length;

    //Call back when body changes
    onCarChanged();
}

//Call when windows are changed
function onWindowChange(offset)
{
    //Find the index which is offset from the current head index by the given offset.
    var offsetIndex = (windowIndex + offset);

    //If negative set index to last image
    if(offsetIndex < 0)
        windowIndex = windowImages.length + offset;

    //Otherwise add offset and modulo by the length to wrap around the values.
    else
        windowIndex = (windowIndex + offset) % windowImages.length;

    //Call back when body changes
    onCarChanged();
}

//Call when car is changed in some way
function onCarChanged()
{
    updateSelectorBox();

    //Set colour and windows images
    windowImage.src = windowImages[windowIndex];
    colourImage.src = colourImages[colourIndex];
}

//Save to local storage
function saveSelection()
{
    localStorage.setItem("chosenColour" , colourIndex);
    localStorage.setItem("chosenWindows" , windowIndex);
}

function loadSelection()
{
    colourIndex = localStorage.getItem("chosenColour");
    windowIndex = localStorage.getItem("chosenWindows");

    onCarChanged()
}

Uncaught ReferenceError: (function) not defined at HTMLButtonElement.onclick

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