Uncaught type error when trying to loop through two element arrays at the same time

Question

enter code herei dunno why it gives me that error "Uncaught typeError: cannot set the property of innerHTML to undefined." for 2 hours it was pain in the ass trying to figure out what's wrong but still didn't conclude anything.... that's my code:

    if(window.addEventListener){
        for(i=0; i<inArray.length; i++){
            inArray[i].addEventListener('keyup',function() {
                if(this.value !== '') document.body.removeChild(text[i]);
                else document.body.appendChild(text[i]);
            },false)
        }
    }else{
        for(i=0; i<inArray.length; i++){
            inArray[i].attachEvent('onkeyup',function() {
                if(this.value !== '') document.body.removeChild(text[i]);
                else document.body.appendChild(text[i]);
            });
        }
    }