Code Snippets for hiding the dependent choice field if there are no dependent choices

Client-Side Components/Client Scripts/Hide Dependent Choice field if there no dependent choices/HideDepnedentField.js

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+function onChange(control, oldValue, newValue, isLoading, isTemplate) {
+    var fieldToHide = 'subcategory'; // I have taken subcategory as an example
+    if (newValue === '') {
+        g_form.setDisplay(fieldToHide, false);
+        return;
+    }
+    var ga = new GlideAjax('NumberOfDependentChoices');
+    ga.addParam('sysparm_name', 'getCountOfDependentChoices');
+    ga.addParam('sysparm_tableName', g_form.getTableName());
+    ga.addParam('sysparm_element', fieldToHide);
+    ga.addParam('sysparm_choiceName', newValue);
+    ga.getXMLAnswer(callBack);
+
+    function callBack(answer) {
+        g_form.setDisplay(fieldToHide, parseInt(answer) > 0 ? true : false);
+    }
+
+}

Client-Side Components/Client Scripts/Hide Dependent Choice field if there no dependent choices/NumberOfDependentChoices.js

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+var NumberOfDependentChoices = Class.create();
+NumberOfDependentChoices.prototype = Object.extendsObject(AbstractAjaxProcessor, {
+    getCountOfDependentChoices: function() {
+		var dependentChoiceCount = 0;
+		var choiceName = this.getParameter('sysparm_choiceName');
+		var tableName = this.getParameter('sysparm_tableName');
+		var element = this.getParameter('sysparm_element');
+		var choiceCountGa = new GlideAggregate('sys_choice');
+		choiceCountGa.addAggregate('COUNT');
+		choiceCountGa.addQuery('dependent_value',choiceName);
+		choiceCountGa.addQuery('inactive','false');
+		choiceCountGa.addQuery('name',tableName);
+		choiceCountGa.addQuery('element',element);
+		choiceCountGa.query();
+		while(choiceCountGa.next()){
+			dependentChoiceCount = choiceCountGa.getAggregate('COUNT');
+		}
+		return dependentChoiceCount;
+	},
+    type: 'NumberOfDependentChoices'
+});

Client-Side Components/Client Scripts/Hide Dependent Choice field if there no dependent choices/README.md

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+Hide the dependent choice field when there are no available options for the selected parent choice.
+
+For example, if a selected category on the incident form has no subcategories, then the subcategory field should be hidden.
+
+The file NumberOfDependentChoices.js is a client callable script include file which has a method which returns number of dependent choices for a selected choice of parent choice field.
+
+HideDepnedentField.js is client script which hides the dependent choice field(ex:subcategory field on incident form) if there are no active choices to show for a selected choices of it's dependent field (example: category on incident form)