JSFiddle - React, Tailwind, and code Playground

HTML

<input type="checkbox" id="leg_rider1" class="abc"/>
<input type="checkbox" id="leg_rider2" class="abc"/>
<input type="checkbox" id="leg_rider3" class="abc"/>
<input type="checkbox" id="leg_rider4" class="abc"/>
<input type="checkbox" id="leg_rider5" class="abc"/>
<input type="checkbox" id="leg_rider6" class="abc"/>
<input type="checkbox" id="leg_rider7" class="abc"/>
<input type="checkbox" id="leg_rider8" class="abc"/>

JavaScript

$("input[type='checkbox'][id^=leg_rider]").change(function(){
    var a = $("input[type='checkbox'][id^=leg_rider]");
    if(a.length == a.filter(":checked").length){
        alert('all checked');
    } else {
        alert('not all checked');
    }
});