This post contains the JSOM examples to enable or disable the access to Master Page customization in SharePoint Site Collection.
The code snippets in below examples used to disable or enable the SharePoint Designer access to Site Owners and Site Designers using SharePoint JSOM.
Properties Used: SP.Site.allowDesigner (SP.js)
The example in this post helps to update and retrieve the title and description of the particular list.
Properties Used: SP.List.title (SP.js) and SP.List.description (SP.js)
The code snippet used to return the collection for content types for the particular SharePoint Web.
Properties Used: SP.Web.ContentTypes (SP.js)
The code snippet which helps to get the collection of available content types from the site and from any of the parent sites.
Properties Used: SP.Web.availableContentTypes property (sp.js)