Dynamic Attributes

Create any custom attribute, even if it's reserved by Webflow

Webflow's custom attributes feature has a powerful data-binding capability that supports binding to CMS fields and component properties- but there are several key limitations;

1. Reserved attributes. many important attribute names are reserved to protect novice web designers. See the notes section below for a list.

2. ECommerce. Collection pages and collection lists that are bound to ECommerce Product and Categories do not support attribute data binding.

SA5's Dynamic Attributes feature overcomes this by allowing you to create proxy attributes that are then applied to the page once the page has loaded.

Use Cases

This is a more technical feature, but it has an incredible range of uses. Here are a few;

• Forms

  • Initialize form field values on INPUTs, TEXTAREAs, SELECTs, CHECKBOXes and other elements with data from a CMS collection item or component property.

    • e.g. Use x:value = ( your value ) to initialize an INPUT, TEXTBOX, or SELECT element from a CMS collection item.

    • e.g. Use x:checked = ( boolean value ) to initialize a checkbox element.

  • Special field configuration

    • e.g. Use x:type = date on an INPUT element to change it to a date type

  • Set hidden form fields to capture data silently, such as the Collection page you're on when the form is submitted.

• Element behavior

  • Such as onclick

• Supporting other SA5 libraries, such as CMS Lightbox Captions and Groups

  • And making these work with ECommerce content

As of 2024-Jun-03, Webflow does not yet support attribute binding to switch ( boolean ) field types or to select ( option ) field types. In a pinch you could use CMS text fields instead.

How it Works

SA5 Dynamic Attributes can be applied in two ways.

1. Custom Attributes. Any attribute created with an x: prefix on the name is specially recognized as an SA5 Dynamic Attribute. It will be processed, and the un-prefixed attribute will then be set to that value. e.g. A custom attribute named x:value would override the value attribute.

2. Custom Embeds. Webflow's embed element can be used to contain a special <script> element, which will be processed and then apply the attribute value to the specified element. As an embed, this is more compatible with ECommerce data-binding.

Getting Started

STEP 1 - Add the Library

First, add the library as detailed in Quick Start.

STEP 2 - Apply x: prefixed custom attributes to any elements

These will overwrite existing attributes on that element. e.g. x:onclick will be applied as onclick on that same element.

Data-bind the value where to CMS fields or component properties where it makes sense.

In previous versions, SA5 also supported dynamic attribute prefixes of x- however we've moved away from that to avoid conflict with Alpine.js which also uses the x- prefix on attributes. Currently this is still supported but considered obsolete.

STEP 3 - Create Embeds where custom attributes cannot work

SA5 Dynamic Attributes use a special embed <script> structure containing a JSON chunk that specifies the target element ( relative to the Embed ), the name of the attribute to set, and the value of that element.

In this example, the style attribute would be created on the parent element containing the Embed, and would be set to a value of font-weight: bold;.

<script type="application/sa5+json" handler="DynamicAttribute">
{
  "@context": "https://attr.sygnal.com",
  "@type": "DynamicAttribute",
  "@version": "0.1",
  "name": "style", 
  "target": "parent", 
  "value": "font-weight: bold;"    
}
</script>

See the usage notes for specific details and advanced use.

Usage Notes

x:* attributes

Create a custom attribute beginning with x: on any element in your page. Set the value you want, and bind it to a CMS field or component property if you want.

x:*:pre attributes

Attributes that are also suffixed with :pre are prepended to the attribute value.

x:*:post attributes

Attributes that are also suffixed with :post are appended to the attribute value.

Embeds

SA5's embed feature has the same capabilities, defined in a JSON chunk.

It must be placed in an Embed, and positioned relative to the element you want the attribute to be applied to, either as a child or as an adjacent sibling.

Here's an example;

<script type="application/sa5+json" handler="DynamicAttribute">
{
  "@context": "https://attr.sygnal.com",
  "@type": "DynamicAttribute",
  "@version": "0.1",
  "name": "style", 
  "target": "parent", 
  "value": "font-weight: bold;", 
  "pre": "font-style: italic;",
  "post": "color: blue;"  
}
</script>

Notes;

• Both the script type and handler are essential

• target can be parent, prev, or next, and identifies the element that the attribute will be applied to

• name indicates the name of the attribute to create or replace

• value ( opional ) indicates the value to set

• pre ( opional ) prefixes the existing or replaced value

• post ( opional ) suffixes the existing or replaced value

Special Element Handling

To assist with the use case of initializing form fields, we've added special handling exceptions for specific element types;

Textarea Elements

Just like an input element, you can use the x:value attribute to initialize the content of a Textarea.

In browsers, Textarea elements behave a bit differently than Input elements. You can initialize them with a value attribute before page load, but if the attribute is set later by script, that value will not be applied. We set the value property as well to ensure it's applied.

Checkbox Elements ( Input type=checkbox )

Use the x:checked attribute directly on the Checkbox element itself. We'll evaluate it as true or false, and set or remove the checked attribute accordingly.

Select Elements

Use the x:value attribute. We'll select the matching option, by value, if it exists.

Note that Select options have both a Name and a Value. It's the Value that is matched, not the Name. Ensure your Values are set correctly.

Notes

Reserved Attribute Names

If you've never encountered it, this is what happens in Webflow when you attempt to use a reserved attribute name.

Here's a partial list of reserved attribute names, as documented by samliew;

abbr, accept, action, align, alt, autofocus, autoplay, bgcolor, border, char, charoff, charset, cite, class, cols, colspan, content, controls, coords, crossorigin, datetime, default, disabled, download, for, form, formaction, formenctype, formmethod, formnovalidate, formtarget, frame, group, headers, height, high, href, hspace, icon, id, ismap, kind, label, list, loop, low, manifest, media, method, multiple, muted, name, optimum, placeholder, poster, preload, radiogroup, readonly, required, reversed, rows, rowspan, sandbox, scheme, scope, scoped, scrolling, seamless, selected, shape, size, sizes, src, srcdoc, srclang, style, type, value, vspace, width, wrap, xmlns, onblur, onclick, ondblclick, ondrag, ondrop, onerror, onfocus, onfocusin, onfocusout, onhelp, oninput, onkeydown, onkeypress, onkeyup, onload, onmousedown, onmouseenter, onmouseleave, onmousemove, onmouseout, onmouseover, onmouseup, onmousewheel, onpaste, onredo, onscroll, onsubmit, onundo

Resources

Custom attributes | Webflow University

Use CMS data in custom attributes | Webflow Features