# API Documentation
<a name="AttributeMarshalling"></a>
## AttributeMarshalling
Mixin which marshalls attributes to properties (and eventually vice versa).

If your component exposes a setter for a property, it's generally a good
idea to let devs using your component be able to set that property in HTML
via an element attribute. You can code that yourself by writing an
`attributeChangedCallback`, or you can use this mixin to get a degree of
automatic support.

This mixin implements an `attributeChangedCallback` that will attempt to
convert a change in an element attribute into a call to the corresponding
property setter. Attributes typically follow hyphenated names ("foo-bar"),
whereas properties typically use camelCase names ("fooBar"). This mixin
respects that convention, automatically mapping the hyphenated attribute
name to the corresponding camelCase property name.

Example: You define a component using this mixin:

    class MyElement extends AttributeMarshalling(HTMLElement) {
      get fooBar() { return this._fooBar; }
      set fooBar(value) { this._fooBar = value; }
    }
    document.registerElement('my-element', MyElement);

If someone then instantiates your component in HTML:

    <my-element foo-bar="Hello"></my-element>

Then, after the element has been upgraded, the `fooBar` setter will
automatically be invoked with the initial value "Hello".

For the time being, this mixin only supports string-valued properties.
If you'd like to convert string attributes to other types (numbers,
booleans), you need to implement `attributeChangedCallback` yourself.

  **Kind**: global class