JSFiddle - React, Tailwind, and code Playground

HTML

<form id="myForm" action="2.php" method="post">
    <input type="checkbox"  name="fruit" id="id1"  class="box" value="Banana"> Banana
    <input type="checkbox"  name="fruit" id="id2"  class="box" value="Cherry"> Cherry
    <input type="checkbox"  name="fruit" id="id3"  class="box" value="Strawberry"> Strawberry
    <input type="checkbox"  name="fruit" id="id4"  class="box" value="Orange"> Orange
    <input type="checkbox"  name="fruit" id="id5"  class="box" value="Peach"> Peach
    <input type="submit" id="groupdelete" value="clickme">
</form>

JavaScript

$("#myForm").submit(function(e) {
    e.preventDefault();     
    var names = [];
    $(this).children('input:checked').each(function() {
        names.push($(this).attr("id")); //it bettern to pass value by using $(this).val()
    });    
    console.log(names); //see the prepared array
    names = names.join(",",names);
    console.log(names);
    $.post("2.php", { 
        "names" : names
    }, function(data) {
        alert(data);        
    });
});