JSFiddle - React, Tailwind, and code Playground

JavaScript

var arrString = 'apple, banana, monkey, sugar',
    text = "This a nice  monkey  zoo with  banana  trees.";

var arr = arrString.split(", ");

var arrMatch = "";

for (var i = 0; i < arr.length; i++) {
    if (text.search(arr[i]) != -1) {
        arrMatch = arr[i];

        //format found item in text
        var text = text.replace(arrMatch, '<b>' + arrMatch + '</b>');

        //Remove found item from array <<<<<< Needs a fix
        if ( i !== -1 ) arr.splice(i, 1);
    }
}

if (arrMatch !== "") {
    $("body").append(arrString + '<br><br>The text contains the array item(s) "' + arrMatch + '".');
}

var arrLeft = arr.join(", ");

$("body").append("<br><br><hr /><br>" + text + "<br><br>These array items are left: " + arrLeft);