How pass the variable in to array JS

Question

The problem is simple. When I take the variable into the array it doesn't work. When I write the variable into inputs it works. How can I pass the variable into the array?

var testW = document.querySelectorAll("input[type='text']");
var testQ = document.getElementsByClassName("deleteObjectbyJS");

var testlength = testW.length;

if(testW[testlength].value == ""){
    testQ[0].style.display = "none";
}

Answer 1

Arrays in JS start indexing from 0 to SIZE-1 so your code is wrong here:

if(testW[testlength-1].value == ""){
    testQ[0].style.display = "none";
}

I don't know if this solve your problem completly but this is an error for sure

Answer 2

testW[testlength]应该是testW[testlength-1]

Answer 3

testlength is length of the list. When you trying to access testW[testlength] you actually access non existing element after the last element because elements indexes are between 0 and testlength-1.