playlist.mp3-youtube-converter.org.js

//https://playlist.mp3-youtube-converter.org/

let downloadForm = document.querySelector('table');
let checkBoxes = downloadForm.querySelectorAll(`[type*="checkbox"]`);

let startArr = parseInt(prompt('select starting number', 'INPUT NUMBER ONLY!'));
let limitArr = 20;
let countArr = limitArr;
countArr = startArr  + countArr
countArr = (countArr > checkBoxes.length ? checkBoxes.length - startArr : limitArr-1);

// check
for (let i = startArr - 1; i < (countArr+startArr); i++) {

    checkBoxes[i].checked = true;
};



// uncheck
for (let i = startArr - 1; i < (countArr+startArr); i++) {
    checkBoxes[i].checked = false;
};