Assigning Item Level permission using JSOM in Sharepoint 2013

This post contains the code to assign Item level permission using JSOM. 

function assignItemLevelPermission()

{

              

                var clientContext = new SP.ClientContext.get_current();

                var collRoleDefinitionBinding;

                var objListItem="your list item"

                collRoleDefinitionBinding = SP.RoleDefinitionBindingCollection.newObject(clientContext);

                    collRoleDefinitionBinding.add(clientContext.get_web().get_roleDefinitions().getByType(SP.RoleType.reader));

                 // Make sure you pass on the user identity as you@youroffice.com

                 var oUser= clientContext.get_web().ensureUser(“you@youroffice.com”);                

                objListItem.breakRoleInheritance(false);

                objListItem.get_roleAssignments().add(oUser, collRoleDefinitionBinding);

                objListItem.update();

                clientContext.load(oUser);

                clientContext.load(objListItem);

                clientContext.executeQueryAsync

                                                (

                                                                function onQuerySucceeded() {

                                                                   alert(‘success’);

                                                                },

                                                                function onQueryFailed() {

                                                                    alert(‘failed’);

                                                                }

                                                );

}