How to make fields conditional?

A conditional field is a field that depends of data collected by one or more fields. The condition is logical value:

  • true, the field is visible and data can be captured,

  • false, the field is not visible and has no value (i.e. value will be removed when switching from true to false condition).

The condition is a short Javascript code. In the context of the execution of this code, the other field values can be accessed with the following syntax:

$('VARIABLE')

where VARIABLE is the name of the field from which the value is to retrieved. When the field is in a group, use a . for building the full name of the field. For instance, if the field with name VARIABLE is in a group with name GROUP, the value of the field will be:

$('GROUP.VARIABLE')

Examples

If the field is a numeric value:

$('VARIABLE') > 12

If the field is an array value (case of multiple choices), to check that there is a value and that 2 choices have been made exactly:

$('VARIABLE') && $('VARIABLE').length === 2

If the field is a string value representing a date, to check that there is a value and that the date is not in the future:

$('VARIABLE') && Date.parse($('VARIABLE')) <= Date.now()