JSFiddle - React, Tailwind, and code Playground

HTML

<ul>
    <li><input type="checkbox" class="spaceTerm" id="2011" name="team" value="2011"/><label for="2011">2011</label></li>
    <li><input type="checkbox" class="spaceTerm" id="2012" name="team" value="2012"/><label for="2012">2012</label></li>
    <li><input type="checkbox" class="spaceTerm" id="2013" name="team" value="2013"/><label for="2013">2013</label></li>
    <li><input type="checkbox" class="spaceTerm" id="archive" name="team" value="archive"/><label for="archive">Archive</label></li>
</ul>

JavaScript

var termString = [];
$('.spaceTerm').on("click", function(){
    $('.spaceTerm').each(function() {
        if ( $(this).is(":checked") ) { termString.push($(this).val()) } else {

}
    })
    
    console.log(termString);
});