JSFiddle - React, Tailwind, and code Playground

HTML

<ul id="MPEditCouleur">
    <li id="lstCoulCompoElemCust1"> 1</li>
    <li id="CoulCompoElemCust1"> 2</li>
    <li id="lstCoulCompoElemCust2"> 3</li>
    <li id="CoulCompoElemCust2"> 4</li>
    <li id="lstCoulCompoElemCust3"> 5</li>
    <li id="CoulCompoElemCust3"> 6</li>
    <li id="lstCoulCompoElemCust4"> 7</li>
    <li id="CoulCompoElemCus5t4"> 8</li>
</ul>

JavaScript

$("#MPEditCouleur li[id^='lstCoulCompoElemCust']").css({"color":"red"})

tab=[]

$("#MPEditCouleur li[id^='lstCoulCompoElemCust']").each( function(){
tab.push($(this).html());})

alert(tab.toSource())