How to save the state of a (switch) button?

Hi there,

this is my first topic, so sorry if i had made something wrong.
I have a problem, i need to save a button state, so after the reload of the webpage it should have the same state, as before. JavaScript ist new too me so i think i make something wrong, i try to solve this problem with localStorage, but it went wrong.
Here is the switch button, which overwritte the button text and change the background color. So i need that if i click on it and it turns from color 1 to color 2 and so on, that this state should be saved, so i can reload the page and the button have the last state. I thank you in advance.

html

<button id="letsgo">
lets go
</button>

<style> #letsgo { background: green; } </style>

javascript
main function:

<script>
onload = init;
function init() {
    var onclick = changeContent();
    var ltsg = document.getElementById("letsgo");
    ltsg.addEventListener("click", onclick, true);
   
}
var state = localStorage.getItem("state");
function changeContent() {
    var count = 0;
    var next = function() {
        switch(count) {
            case 0:
            // function click 1 here
            document.getElementById("letsgo").style.backgroundColor = "red";
            document.getElementById("letsgo").innerHTML = "stop";
          
            break;
            case 1:
            // function click 2 here
            document.getElementById("letsgo").style.backgroundColor = "green";
            document.getElementById("letsgo").innerHTML = "lets go";
           
          break;
          }
            if (count  === 0)
        {
        		localStorage.setItem("state", count);
            count++;
            
        }
        else {
        		localStorage.setItem("state", count);
            count = 0;
            
        }
    }
    return next;

}
</script>

how i try to solve this problem:

<script>
onload = init;
function init() {
    var onclick = changeContent();
    var ltsg = document.getElementById("letsgo");
    ltsg.addEventListener("click", onclick, true);
   
}

var state = localStorage.getItem("state");
var count = 0;

function saveit() {
if (state === 0) {
function changeContent() {
   count = 0;
    var next = function() {
        switch(count) {
            case 0:
            // function click 1 here
            document.getElementById("letsgo").style.backgroundColor = "red";
            document.getElementById("letsgo").innerHTML = "stop";
          
            break;
            case 1:
            // function click 2 here
            document.getElementById("letsgo").style.backgroundColor = "green";
            document.getElementById("letsgo").innerHTML = "lets go";
           
          break;
          }
            if (count  === 0)
        {
        		localStorage.setItem("state", count);
            count++;
            
        }
        else {
        		localStorage.setItem("state", count);
            count = 0;
            
        }
    }
    return next;
    }
    }
else {
function changeContent() {
     count = 1;
    var next = function() {
        switch(count) {
          case 1:
            // function click 2 here
            document.getElementById("letsgo").style.backgroundColor = "green";
            document.getElementById("letsgo").innerHTML = "lets go";
           
          break;
            case 0:
            // function click 1 here
            document.getElementById("letsgo").style.backgroundColor = "red";
            document.getElementById("letsgo").innerHTML = "stop";
          
            break;
          
          }
            if (count  == 1)
        {
        		localStorage.setItem("state", count);
            count = 0;
            
        }
        else {
        		localStorage.setItem("state", count);
            count ++;
            
        }
    }
    return next;
    }
    }
}
</script>