HTMLInputElement.multiple

The HTMLInputElement.multiple property indicates if an input can have more than one value. Firefox currently only supports multiple for <input type="file">.

// fileInput is a <input type=file multiple>
let fileInput = document.getElementById('myfileinput');

if (fileInput.multiple == true) {

  for (let i = 0; i < fileInput.files.length; i++) {
    // Loop fileInput.files
  }

// Only one file available
} else {
  let file = fileInput.files.item(0);
}

• FileList
• Bug 523771 - Support <input type=file multiple>