Using WordPress ‘is_object_in_term()’ PHP function
Determines if the given object is associated with any of the given terms.
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Using WordPress ‘is_object_in_taxonomy()’ PHP function
Determines if the given object type is associated with the given taxonomy.
Using WordPress ‘is_new_day()’ PHP function
Determines whether the publish date of the current post in the loop is different from the publish date of the previous post in the loop.
Using WordPress ‘is_network_only_plugin()’ PHP function
Checks for “Network: true” in the plugin header to see if this should be activated only as a network wide plugin. The plugin would also work when Multisite is not…
Using WordPress ‘is_network_admin()’ PHP function
Determines whether the current request is for the network administrative interface.
Using WordPress ‘is_nav_menu_item()’ PHP function
Determines whether the given ID is a nav menu item.
Using WordPress ‘is_nav_menu()’ PHP function
Determines whether the given ID is a navigation menu.
Using WordPress ‘is_multi_author()’ PHP function
Determines whether this site has more than one author.
Using WordPress ‘like_escape()’ PHP function
Formerly used to escape strings before searching the DB. It was poorly documented and never worked as described.