JSFiddle - React, Tailwind, and code Playground

HTML

<form id="myForm" name="myForm" method="post" action="">
    
    task : 35
    <select name="compName-35-1" id="compName-35-1">
        <option value=""></option>
        <option value="acme inc::30">acme inc::30</option>
        <option value="my company::54781">my company::54781</option>
        <option value="abc llc::42443">abc llc::42443</option>
        <option value="zzzz">zzzz</option>
    </select> 
    
    <select name="compName-35-2" id="compName-35-2" style="padding-left:20px;">
        <option value=""></option>
        <option value="acme inc::30">acme inc::30</option>
        <option value="my company::54781">my company::54781</option>
        <option value="abc llc::42443">abc llc::42443</option>
        <option value="zzzz">zzzz</option>
    </select> 
    <hr/>
    
    task : 36
    <select name="compName-36-1" id="compName-36-1">
        <option value=""></option>
        <option value="acme inc::30">acme inc::30</option>
        <option value="my company::54781">my company::54781</option>
        <option value="abc llc::42443">abc llc::42443</option>
        <option value="zzzz">zzzz</option>
    </select> 
    
    <select name="compName-36-2" id="compName-36-2" style="padding-left:20px;">
        <option value=""></option>
        <option value="acme inc::30">acme inc::30</option>
        <option value="my company::54781">my company::54781</option>
        <option value="abc llc::42443">abc llc::42443</option>
        <option value="zzzz">zzzz</option>
    </select> 
    <hr/>
    
    task : 37
    <select name="compName-37-1" id="compName-37-1">
        <option value=""></option>
        <option value="acme inc::30">acme inc::30</option>
        <option value="my company::54781">my company::54781</option>
        <option value="abc llc::42443">abc llc::42443</option>
        <option value="zzzz">zzzz</option>
    </select> 
    
    <select name="compName-37-2" id="compName-37-2" style="padding-left:20px;">
        <option...

JavaScript

Array.prototype.unique =

function() {
    var a = [];
    var l = this.length;
    for (var i = 0; i < l; i++) {
        for (var j = i + 1; j < l; j++) {
            if (this[i] === this[j]) j = ++i;
        }
        a.push(this[i]);
    }
    return a;
};


$('select[name^=compName]').change(function() {
    var tid = $(this).attr('name').split('-')[1];
    var j = $(this).attr('name').split('-')[2];
    var currTaskIDs = $("#taskIDList").val();

    // begin: create the task list:
    var arr = [];

    if (currTaskIDs.length) arr = currTaskIDs.split(',');
    if (tid.length) arr.push(tid);

    var u = arr.unique();

    $("#taskIDList").val(u.join(','));
    // end
});