I am trying to validate user input to see if they enter a number and show an error if they enter anything that's not a number.

here is the html element

<input type="text" id="user_input">

here is my javascript

let user_input = Number(document.querySelector("#user_input").value);

if (user_input == NaN) {
    console.log("its not a number");
} else {
    console.log("its a number");
}

Here, when I enter a string, it still says "its a number" on the console. Why is this happening?