GlideForm API ServiceNow | How to dynamically display the choices in my select box field | g_form.addOption

GlideForm.js is the JavaScript class containing the methods. The global object g_form is used to access GlideForm methods. GlideForm methods are only used on the client. Or g_form.addOption dynamically display the choices in my select box field.
addDecoration(fieldName, String icon, String title)

g_form.addDecoration('requested_for', 'icon-star', 'preferred member');

Displays the specified error message at the top of the form.

g_form.addFormMessage('info message','info');
g_form.addFormMessage('error message','error');
g_form.addFormMessage('info2 message','info');
g_form.addFormMessage('warning2 message','warning');
g_form.addFormMessage('error2 message','error');
g_form.addFormMessage('warning message','warning');

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addOption(String fieldName, String choiceValue, String choiceLabel)

g_form.addOption('priority', '6', '6 - Really Low');

clearMessages()

1. g_form.clearMessages();

disableAttachments() (Prevents file attachments from being added.)
enableAttachments() (Allows file attachments to be added. Shows the paper clip icon.)

Flashes the specified color for a specified duration of time in the specified field.

g_form.flash("number", "#FFFACD", 0);

Returns the most recent action name, or, for a client script, the sys_id of the UI action clicked.

function onSubmit() {
 var action = g_form.getActionName();
 alert('You pressed ' + action);
 }

How to get the display value from a form in the core UI

g_form.getDisplayBox('caller_id').value;

How to get the display value from a form

g_form.getDisplayValue();

How to Returns the HTML element for the form

g_form.getFormElement()

How to Returns the HTML element of the help text for the specified field.

g_form.getHelpTextControl(String fieldName)

How to Returns the option element for a selected box named fieldName where choiceValue matches the option value.

g_form.getOption('category', choiceValue).text;

Returns an array of related list names from the current form.

var getListNames = g_form.getRelatedListNames();

for (var i = 0; i < getListNames.length; i++) {

this.showRelatedList(getListNames[i]);

}

Returns all section names, whether visible or not

g_form.getSections();

How to Returns an array of the form's sections.

function onChange(control, oldValue, newValue, isLoading) {
 var sections = g_form.getSections();
if (newValue == '3') {
g_form.setSectionDisplay(sections[1], false);
} else {
g_form.setSectionDisplay(sections[1], true);
}
}

Returns true if the field is mandatory

g_form.isMandatory(String fieldName)