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JavaScript Help With Javascript Loop


New Coder
Hello - I want to take the filename from a file input and then populate in some text inputs, doesn't work correctly and only one text input is populated:

<meta charset="utf-8">

    <input type="file" id="fileinput"><br>
    <input type="text" id="textinput_1" class="countme"><br>
    <input type="text" id="textinput_2" class="countme"><br>
    <input type="text" id="textinput_3" class="countme"><br>
    <input type="text" id="textinput_4" class="countme">

const countAll = document.querySelectorAll('.countme').length; // Count elements
console.log(countAll); //  3
for (let i = 1; i < countAll; i++) {

  const textinput = document.getElementById('textinput_' + i); // textinput_1, textinput_2, etc
  document.getElementById('fileinput').oninput = function() {
    textinput.value = document.getElementById('fileinput').files[0].name;
Indeed it only populates the third textfield.
Why the third ? Because you miss the last element in your loop. The condition should be i <= countAll.
If you correct that, you'll see it now only populates the last textfield.
Why only the last ? Because you define the oninput function four times inside your loop. So only the last definition (which is for the 4th element) sticks.

You need to define the function once, and place the loop inside it:

document.getElementById('fileinput').oninput = function()
    for (i = 1; i <= countAll; i++)
        const textinput = document.getElementById('textinput_' + i); // textinput_1, textinput_2, etc
        textinput.value = document.getElementById('fileinput').files[0].name;

That will work. But note that you should always start loops from zero, not one.
Or much better still, get rid of the loop counter and simply write

document.getElementById('fileinput').oninput = function()
    for (t of document.querySelectorAll('.countme'))
        t.value = document.getElementById('fileinput').files[0].name;
Now you're also not dependent on the name of the textinput elements.

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