Validar tamanho do arquivo em JS

function validateSize(input) {
  const fileSize = input.files[0].size / 1024 / 1024; // in MiB
  if (fileSize > 2) {
    alert('File size exceeds 2 MiB');
    // $(file).val(''); //for clearing with Jquery
  } else {
    // Proceed further
  }
}

<input onchange="validateSize(this)" type="file">
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