function checkFile()

in public/js/main.js [96:123]

• 24 lines of code
• 4 McCabe index (conditional complexity)

function checkFile() {
    if (fileInputEl.files.length === 0) {
       uploadBtnEl.setAttribute('disabled', 'disabled');
       return;
    }

    var isZipFile = (fileInputEl.files[0].type === 'application/zip');
    if (!isZipFile) {
        uploadBtnEl.setAttribute('disabled', 'disabled');
        showMsg(messages.wrongType);
        return;
    }

    step1El.style.display = 'none';
    step2El.style.display = 'block';
    [].forEach.call(stepNumEls, function(el , i) {
        if (i === 1) { el.classList.toggle('disabled', false); }
        else { el.classList.toggle('disabled', true); }
    });

    var zipFile = fileInputEl.files[0];
    var reader = new FileReader();
    reader.onload = readZipFile(zipFile);
    reader.readAsArrayBuffer(zipFile);

    uploadBtnEl.removeAttribute('disabled');
    hideMsg();
}