====== Hidden Fields ======

The **Hidden Field** is used as a temporary storage of either a value or an array of values. The field is invisible on the device. 

{{::hidden_field_button.png?nolink&120| }}Click on the Hidden Field button to add a hidden field to any page in your app. Like any other input or output field, the value of this field can be used in a JavaScript statement or as an input or output of a web service or a database field value. There is a **Default Value** property that you can preset to a fixed value, such as a URL, or you may leave this blank.

===== Typical Usage =====

Typically, a Hidden Field is used to store something in a delayed action or store a hidden value. 

For example, the value from a data source may be a decimal number, but you want to show a Text Label field that looks like a percentage. The steps are:
  - The data query writes to a Hidden Field instead of the Text Label field
  - JavaScript code after the query computes the Text Label field based on the Hidden Field.

JavaScript code for this example might look like this:
<code>
var showPercent = ( getFieldValue( 'hidden_percent' ) * 100 ) + '%';
setFieldValue( 'showPercentLabel', showPercent );
</code>

===== Device ID =====

The **Hidden Field** properties have a second option besides the Default Value. Select the **Set Value To** property as **Device ID**, and the hidden field will report a unique identifier for that specific device. The Device ID is often used to register unique devices for individual users, or can be used to distinguish unique users without requiring a user login, such as collecting responses to a survey.
{{ ::hidden_field_device_id.png?direct&350 |}}