write java script function

Job ID: 30997470

Budget: €8 – €30 EUR

i want java script function to add f letter end of the text input has been added from user

the input text is in type of password
so after user enter the password i want this letter to be added end of user input one time only
and it should be hidden means if user want to click on show password he entered or unhide it he should not see this addetional letter added to the end .

for testing you can do it on https://www.w3schools.com/ and show me that it works so i can apply on my side


thank you