Editing GTM Data Layer

This JavaScript is added in the header of the website:

<syntaxhighlight lang="javascript">
window.dataLayer = window.dataLayer || [];
function gtag() {
    dataLayer.push(arguments);
}
</syntaxhighlight>

The `dataLayer` collection is sent to Google Tag Manager. 

The `gtag()` function is a convenience for sending this data. 

After the document content is loaded, it can be used to send event data to GTM.

<syntaxhighlight lang="javascript">
gtag("event", "purchase", {
    transaction_id: "BFH_5478",
    value: 10,
    tax: 0,
    shipping: 0,
    currency: "USD",
    payment_method: "PayPal credit card",
    items: [
        {
            item_id: "PB-DL",
            item_name: "Playful Beginnings, with Overview, the Teacher&#39;s Guide",
            affiliation: "Barchowsky Fluent Handwriting Website",
            coupon: "",
            discount: 0,
            price: 10.00,
            item_brand: "Barchowsky Fluent Handwriting",
            item_variant: "download",
            quantity: 1
        },
    ]
});
</syntaxhighlight>

The above has the same effect as 

<syntaxhighlight lang="javascript">
dataLayer.push({event: "purchase", ...});
</syntaxhighlight>

Pointing that out because on the website, there can be calls to `gtag()`, while in a tutorial video I was watching the code displayed was `dataLayer.push()`

[[Category:Web Development]][[Category:Analytics]]