Focus on a widget annotation

Q: How to focus on a widget annotation programmatically?

A: You can set the focus on a widget annotation programmatically using the DOM API. The next example adds a custom toolbar item that focuses a form field when clicked. Remember that you would need to adjust the selector with a valid form field name:

let instance = null;

PSPDFKit.load({
    ...defaultConfiguration,
    toolbarItems: [
      ...PSPDFKit.defaultToolbarItems,
      {
        type: "custom",
        title: "Focus",
        onPress() {
          instance.contentDocument
            .querySelector(".PSPDFKit-Annotation-Widget[name='form field name']")
            .focus();
        }
      }
    ]
  }).then(_instance => {
    instance = _instance;
});

If the widget annotation is associated to a text form field you can also automatically set the selection to the end of the current value of the input using the HTMLInputElement.setSelectionRange method:

let instance = null;

PSPDFKit.load({
    ...defaultConfiguration,
    toolbarItems: [
      ...PSPDFKit.defaultToolbarItems,
      {
        type: "custom",
        title: "Focus",
        onPress() {
          const element = instance.contentDocument.querySelector(
            ".PSPDFKit-Annotation-Widget[name='form field name']"
          );
          element.focus();
          element.setSelectionRange(element.value.length, element.value.length);
        }
      }
    ]
  }).then(_instance => {
    instance = _instance;
});

This has been tested with PSPDFKit for Web 2019.5.4.