Question

I have a lot input boxes and I need to make a condition that checks if all of them are empty how can I do this in javascript with a single variable. This is what I have, but it only checks 1 box

function boxes() {

    var box_a = document.getElementById('box_a');

         if(box_a==="")   {
            alert("box not filled")
               return false;
          } 

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

Answer 1

Try like this:

var textinputs = document.querySelectorAll('input[type=text]');

var empty = [].filter.call( textinputs, function( el ) {
   return !el.value
});

if ( textinputs.length == empty.length ) {
  // all text inputs are empty
}