JSFiddle - React, Tailwind, and code Playground

JavaScript

function splitter(mystring, mysplitter) {
    var myreturn = [],
        myindexplusone = mystring.indexOf(mysplitter) + 1;

    if (myindexplusone) {
        myreturn[0] = mystring.split(mysplitter, 1)[0];
        myreturn[1] = mystring.substring(myindexplusone);
    }

    return myreturn;
}

var str = splitter("hello-world-this-is-a-test", "-");

document.write(str.join("<br>"));
//hello
//world-this-is-a-test