UI actions include the buttons, links, and context menu items on forms and lists.

Configure UI actions to make the UI more interactive, customized, and specific to user activities.

There are two ways to override UI action:

1. Complete the following steps to override a UI action on the Task table for just the Incident table.
- Create a UI action on the Incident table with the same Action name.If the Action name is not defined, use the same Name. Enter a script that is specific to the Incident table.
- Complete the following steps to remove a UI action on the Task table for the Incident table. Navigate to the UI action definition for the Task table. Add the condition current.getRecordClassName() !='incident'.

2. We can override the parent table UI action on the child table via setting the 'Override' field.

Based on the type of script, it could be divided into 3 types:
1. Client Side.
2. Server Side.
3. Client as well as Server Side.

Based on it's position on the form, it could be divided into following types:
1. Button on a form.
2. Context menu item on a form that appears when you open the form context menu or right-click the form header.
3. Related link in a form.
4. Button in the banner on top of a list.
5. Button at the bottom of a list.
6. Context menu item on a list that appears when you open the list context menu or right-click the list header.
7. Menu item for the action choice list at the bottom of a list.
8. Related link at the bottom of a list.

Based on the table, it could be divided into following types:
1. Global UI actions.
2. Table UI action.

To write Server and Client side script in UI action, we need to use gsftSubmit method as shown below:

//Client-side 'onclick' function
function runClientCode(){
if( == false){
return false; //Abort submission
}

//Call the UI Action and skip the 'onclick' function
gsftSubmit(null, g_form.getFormElement(), ''); //MUST call the 'Action name' set in this UI Action
}

//Code that runs without 'onclick'
//Ensure call to server-side function with no browser errors
if(typeof window == 'undefined')
runBusRuleCode();

//Server-side function
function runBusRuleCode(){
current. = ;
current.update();
gs.addInfoMessage('You did it!');
action.setRedirectURL(current);
}

For more details, please refer link :Client and Server Code in One UI Action