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fires before a Form control or its element is shown

beforeShow: (name: string, value?: any, id?: string) => boolean | void;


  • name|id: string - the name (or id, if the name is not specified) of the Form control
  • value?: any - optional, the current value of the control
  • id?: string - optional, the id of the element of the control of Form (for RadioGroup, CheckboxGroup)


Return false to prevent a control from being shown; otherwise, true.

Example"beforeShow", function(name, value) {
console.log("beforeShow", name, value);
return false;

Change log:

  • The id parameter was added in v8.0
  • Before v7.0, the event took one parameter - the control id.
  • Starting from v7.0, the event takes two parameters: name|id and value.
  • The event was added in v6.5