JSFiddle - React, Tailwind, and code Playground

HTML

<div class="calcStartPrice">
    <span id="eventStartPrice_S20_L10140"></span>
    <span id="S20_L10140_startPrice"></span>
    <span id="exchangeRate_S20_L10140"></span>
    <span id="curSymbol_S20_L10140"></span>
    <span id="decPlaces_S20_L10140"></span>
    <span id="converted_StartPrice_S20_L10140"></span>
</div>

JavaScript

var eventStartPrice;
jQuery(".calcStartPrice").each(function (i,e) {
    jQuery(e).find('span, input').each(function (a,b) {
        //console.info(b.id);
        var $this = jQuery(this);
        if ($this.is("[id^=eventStartPrice]")) { //this is wrong!!!
            eventStartPrice = $this.attr("id");
            console.info(eventStartPrice);
        }
    });
});