Some stupid mistake.

When you are working, you make stupid mistakes. Keep reminding yourself at any time on your podcast.

Variable declaration elevation for a function:
function items () {Console.log (' a ')} Such functions are declared in such a way that the whole function is lifted up and the function can be called before the function declaration.
var items = function () {alert (1)} This is the way that functions are declared, and variable declaration promotion will elevate the items variable name up to the function declaration. Variable names can be called, but functions cannot be called

Some stupid mistake.