Why does this placeholder attribute get passed through?

Question

I am working on a JSF 2.1 application and I noticed some funny code that looks like this:

<h:inputText value="someValue" h:placeholder="Please enter a value" />

Notice that the placeholder is incorrectly prefixed with the JSF html namespace. For some reason this code works and it results in the placeholder attribute being rendered.

I am using the OmniFaces RenderKitFactory, but as you can see below I haven't defined the placeholder attribute on HtmlInputText:

<context-param>
    <param-name>org.omnifaces.HTML5_RENDER_KIT_PASSTHROUGH_ATTRIBUTES</param-name>
    <param-value>
    javax.faces.component.html.HtmlForm=role;
    javax.faces.component.html.HtmlInputText=type;
    javax.faces.component.html.HtmlInputText=step;
    javax.faces.component.html.HtmlInputText=min;
    javax.faces.component.html.HtmlInputText=list;
    javax.faces.component.html.HtmlInputText=max;
    javax.faces.component.html.HtmlInputText=required;
    javax.faces.component.html.HtmlCommandButton=data-target;
    javax.faces.component.html.HtmlCommandButton=data-toggle;            
</param-value>
</context-param>

Why does this work?

http://docs.oracle.com/javaee/7/tutorial/jsf-facelets009.htm#sthref393 .. check this — RïshïKêsh Kümar, Jun 07 '17 at 06:54
Hi RïshïKêsh, It is a JSF 2.1 application so it is not possible to use the passthrough attribute namespace... — Duran Wesley Harris, Jun 07 '17 at 06:56
https://stackoverflow.com/questions/8494264/how-to-add-placeholder-attribute-to-jsf-input-component .. — RïshïKêsh Kümar, Jun 07 '17 at 07:01
You are using omnifaces as you stated in another question. Most likely omnifaces is passing on this element (it is one of the otions in the referred answer) — Kukeltje, Jun 07 '17 at 08:22
Hi Kukeltje, I have not specified the placeholder attribute for HtmlInputText on the RenderKitFactory. I edited the post to show the render kit configuration. — Duran Wesley Harris, Jun 07 '17 at 08:25

score 1 · Accepted Answer · answered Aug 01 '17 at 10:00

The Omnifaces HTML5 RenderKit supports several HTML5 attributes by default. The attributes that you specify in the web.xml are additional attributes.

The values which are supported by default are, as per the JavaDoc,

UIForm:
- autocomplete
UISelectBoolean, UISelectOne and UISelectMany:
- autofocus
HtmlInputTextarea:
- autofocus
- maxlength
- placeholder
- spellcheck
- wrap
HtmlInputText:
- type (supported values are text (default), search, email, url, tel, range, number and date)
- autofocus
- list
- pattern
- placeholder
- spellcheck
- min
- max
- step
(the latter three are only supported on type of range, number and date)
HtmlInputSecret:
- autofocus
- pattern
- placeholder
HtmlCommandButton:
- autofocus

Why does this placeholder attribute get passed through?

1 Answers1