How to set a default value based on user's previous value

I want to have a default value based on what the user put before. For example, if in an input I put '5' I want to see that the value of that input is 5 when I refresh the page, but if I put 6 I want the default value to be 6. Thanks (i'm a begginer)

Solution

Use local storage:

localStorage = window.localStorage;
localStorage.setItem('inputDefault', '5');

let inputDefault = localStorage.getItem('inputDefault');

Here's a more practical example I quickly whipped up:

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Local Storage Example</title>

    <script type="text/javascript">
        function setLocalStorageValue()
        {
            let myNumberInputField = document.getElementById('myNumberInput');
            let myNewValue = myNumberInputField.value;

            let localStorage = window.localStorage;
            localStorage.setItem('defaultValue', myNewValue);
        }

        function getLocalStoredValue()
        {
            let localStorage = window.localStorage;
            let defaultValue = localStorage.getItem('defaultValue');

            let myNumberInputField = document.getElementById('myNumberInput');
            myNumberInputField.value = defaultValue;
        }
    </script>
</head>
<body onload="getLocalStoredValue()">
<label>My Number Input
    <input type="number" id="myNumberInput" value="0" onchange="setLocalStorageValue()">
</label>
</body>
</html>

Does this answer your question? Note how I am writing back to local storage on the onchange event of the input in question, and I read from local storage when the body of the html loads.