Defines a custom template for the start affix area of the built-in message box. The start affix is positioned before the input field. This option applies when messageBoxTemplate is not set.

In the built-in PromptBox-backed Chat message box, the file attachment button belongs to the start affix. If the template does not include a matching ref-promptbox-file-select-button element, Chat backfills the enabled attachment button before the authored start-affix content inside the same start-affix container.

Example

<div id="chat"></div>
<script>
$("#chat").kendoChat({
    authorId: "user",
    messageBox: {
        startAffixTemplate: () => '<span class="k-icon k-i-star"></span>'
    }
});
</script>