Mulitple JS errors - OptionsPrice undefined - Magento 1.9.3.4

[fairport]

TypeError: Cannot read property 'prototype' of undefined
at scp_product_extension.js:123

Uncaught TypeError: Cannot read property 'changePrice' of undefined
at klass.reloadPrice (configurable.js:286)

OptionsPrice == 'undefined' is the main issue.

These plus a number of issues are making this unusable in my 1.9.3.4 site.

[codebymikey]

Plus one. Having the same issue. Fixed it.

Turned out to be an issue with my catalog.xml file.
Adding the <action method="addJs"><script>varien/product_options.js</script></action> line under my catalog_product_view tag worked like so worked:

    <catalog_product_view translate="label">
        <label>Catalog Product View (Any)</label>
        <!-- Mage_Catalog -->
        <reference name="root">
            <action method="setTemplate"><template>page/1column.phtml</template></action>
        </reference>
        <reference name="head">
            <action method="addJs"><script>varien/product.js</script></action>
            <action method="addJs"><script>varien/configurable.js</script></action>
            <action method="addJs"><script>varien/product_options.js</script></action>
<!-- // ... -->

[allemas]

I had the same issue.

Uncaught TypeError: Cannot read property 'prototype' of undefined
at scp_product_extension.js:123

and

configurable.js:286 Uncaught TypeError: Cannot read property 'changePrice' of undefined
at klass.reloadPrice (configurable.js:286)
at klass.configureElement (configurable.js:137)
at klass.configure (configurable.js:121)
at HTMLSelectElement. (prototype.js:391)
at HTMLSelectElement.responder (prototype.js:5598)
at triggerEvent (script.js:285)
at HTMLAnchorElement. (script.js:157)
at HTMLDocument.dispatch (jquery-1.8.3.min.js:2)
at HTMLDocument.u (jquery-1.8.3.min.js:2)

It worked for me !

Dont forget to edit all layouts where you use products configurations.
varien/... is for rdw base theme, if you use another, adapt the path.