Question

I am trying to save form data to localstorage on keyup event with javascript. I have the following code but I get the error “Uncaught TypeError: Cannot set property ‘onkeyup’ of null”.

html

<input type="text" id="username" />

javascript

var user = document.getElementById("username");
user.onkeyup = function(){
    localStorage.setItem('user', user.value);
};

Answer 1

You are trying to access DOM element before loaded is completed. wrap your code inside a function and call in window.onload

function init() {
var user = document.getElementById("username");
user.onkeyup = function(){
    localStorage.setItem('user', user.value);
};
}
window.onload = init;