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Customize PDF form field styles with JavaScript

Change the color and opacity of PDF Form Fields using this JavaScript sample (no servers or other external dependencies required). This is commonly used to highlight required fields in a form (signature fields) or to make important fields easier to find on a page. This sample works on all browsers (including IE10) and mobile devices without using plug-ins. To see an example launch our Form Field Customization demo. Learn more about our JavaScript PDF Library.

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  path: '../../../lib',
  pdftronServer: '', // comment this out to do client-side only
  initialDoc: ''
}, document.getElementById('viewer'))
  .then(function(instance) {
    var docViewer = instance.docViewer;
    var annotManager = instance.annotManager;
    var Annotations = instance.Annotations;

    docViewer.on('documentLoaded', function() {
      var pageCount = docViewer.getPageCount();
      var defaultStyles = Annotations.WidgetAnnotation.getCustomStyles;
      var customStyles = function(widget) {
        if (widget instanceof Annotations.TextWidgetAnnotation) {
          if (widget.fieldName === 'f1-1') {
            return {
              'background-color': 'lightgreen'
          return {
            'background-color': 'lightblue',
            color: 'brown'
        } else if (widget instanceof Annotations.PushButtonWidgetAnnotation) {
          return {
            'background-color': 'red',
            color: 'white'

      document.getElementById('form').onchange = function(e) {
        if ( === 'custom') {
        // Change styles for widget annotations
          Annotations.WidgetAnnotation.getCustomStyles = customStyles;
        } else {
          Annotations.WidgetAnnotation.getCustomStyles = defaultStyles;
        for (var i = 0; i < pageCount; i++) {
        // Redraw canvas
          annotManager.drawAnnotations(i + 1, null, true);

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