html-demo-element advanced use

Programmatic content switch

<fieldset>
    <legend> demoElement.source = node </legend>
    <button onclick="setSourceByNode( 'css' )"> css   </button>
    <button onclick="setSourceByNode( 'js'  )"> js    </button>
    <button onclick="setSourceByNode( 'html')"> html  </button>
</fieldset>
<fieldset>
    <legend> demoElement.source = text of </legend>
    <button onclick="setSourceProp( 'css' )"> css   </button>
    <button onclick="setSourceProp( 'js'  )"> js    </button>
    <button onclick="setSourceProp( 'html')"> html  </button>
</fieldset>
<fieldset>
    <legend> set source attribute from text of </legend>
    <button onclick="setSourceAttribute( 'css' )"> css   </button>
    <button onclick="setSourceAttribute( 'js'  )"> js    </button>
    <button onclick="setSourceAttribute( 'html')"> html  </button>
</fieldset>