Highlight elements on a website and get the JavaScript code for retrieval - shown in Chrome Developer Console.
GTM Variable Builder:
How to use - Highlight an area on a website (text only), the price, the product id, or the name of a page. Then click the extension icon. Goto the JS console in chrome and view the output, the retrieval of what you highlighted will be there.
Test your generated JavaScript in the console. If it returns what you've highlighted, copy the generated function into a custom javaScript variable in Google Tag Manager.
Cheers,
Alessandro