How to run javascript only once after every login? -

i trying achieve after user logs in app, have send request servlet, respond servletoutputstream sound message ('hello user, how you'). want once, not after logged user refreshes page , hears again.

you can use localstorage general solution.

check if user received message before outputting message:

if (!localstorage.getitem('messagesent')) {     // 1. create message user here      // 2. make sure user not message again     localstorage.setitem('messagesent', 'true'); // truthy value } 

clear localstorage when user logs out:

localstorage.removeitem('messagesent'); 

based off question, seems can avoid above solution , output message in login logic (after user gets authenticated , logs in). when user refreshes page, shouldn't show message because login logic should not run when user logged in.