validation login with data stored on localStorage

the code i made only reads the last index from localStorage for login validation, can someone help to login using all existing data?

$('#btnlogin').click(function(){
        var usernamelogin = $('#usernamelogin').val()
        var passwordlogin = $('#passwordlogin').val()
        var data_user1 = JSON.parse(localStorage.getItem('data_user'))
        
        for(var i in data_user1){
        var entry = data_user1[i]
        }
        
        if(usernamelogin == entry.username && passwordlogin == entry.password){
            alert("Log in successfull")
            window.location.href = "curhat.jsp"
        }else{
            alert("wrong username or password")
            }           
        //console.log(data_user1)
        //console.log('username = ' + entry.username)
        
    })