Check if DOM Element is a checkbox

Checks anything

function isCheckbox (element) {
   return element instanceof HTMLInputElement 
      && element.getAttribute('type') == 'checkbox'
}

If you're using jQuery, you can use the :checkbox pseudo-class selector along with is method:

if($("#that-particular-input").is(":checkbox")) {
}

Using only vanilla javascript you could do

if (el.type && el.type === 'checkbox') {
   ...
}

or even shorter

if ((el || {}).type === 'checkbox') {
   ...
}

or in modern browsers you could use matches()

if (el.matches('[type="checkbox"]') {
    ...
}