Adding Item to ECB (Edit control Block) menu

Add Item in Ellipsis menu.

Steps

Step1:

Edit List Page and Add Script Editor web part.

Step2:

Add this Script to Script editor web part

<script type="text/javascript">

function Custom_AddDocLibMenuItems(m, ctx)

{

 var strDisplayText = "Publish to Market Research"; //Menu Item Text

 var strAction = "alert('Hello World')"; //Menu item action

 var strImagePath = ""; //Menu item Image path

 // Add our new menu item

 CAMOpt(m, strDisplayText, strAction, strImagePath);

 // add a separator to the menu

 CAMSep(m);

 // false means that the standard menu items should also be rendered

 return false;

}

</script>

Add Item in ECB Menu

Step1:

Edit List Page and Add Script Editor web part.

Step2:

Add this Script to Script editor web part

<script type="text/javascript">

SP.SOD.executeFunc("callout.js", "Callout", function () {

 var itemCtx = {};

 itemCtx.Templates = {};

 itemCtx.BaseViewID = 'Callout';

 // Define the list template type

 itemCtx.ListTemplateType = 101;

 itemCtx.Templates.Footer = function (itemCtx) {

   // context, custom action function, show the ECB menu (boolean)

   return CalloutRenderFooterTemplate(itemCtx, AddCustomAction, true);

 };

 SPClientTemplates.TemplateManager.RegisterTemplateOverrides(itemCtx);

});

function AddCustomAction (renderCtx, calloutActionMenu) {   

 // Add your custom action

 calloutActionMenu.addAction (new CalloutAction ({

   text: "Custom Action",

   tooltip: 'This is your custom action',

   onClickCallback: function() { console.log('Callback from custom action'); }

 }));

 // Show the default document library actions

 CalloutOnPostRenderTemplate(renderCtx, calloutActionMenu);

 // Show the follow action

 calloutActionMenu.addAction(new CalloutAction({

   text: Strings.STS.L_CalloutFollowAction,

   tooltip: Strings.STS.L_CalloutFollowAction_Tooltip,

   onClickCallback: function (calloutActionClickEvent, calloutAction) {

     var callout = GetCalloutFromRenderCtx(renderCtx);

     if (!(typeof(callout) === 'undefined' || callout === null))

       callout.close();

     SP.SOD.executeFunc('followingcommon.js', 'FollowSelectedDocument', function() { FollowSelectedDocument(renderCtx); });

   }

 }));

}

</script>

Reference Link

http://www.eliostruyf.com/adding-a-custom-action-to-a-callout-in-sharepoint-2013/