JSFiddle - React, Tailwind, and code Playground

JavaScript

var name = 'John M Peters';
var arr = name.split(' ');

var obj = {fname: arr[0]};
if(arr.length === 1) {
    obj.lname = arr[1];
} else {
    obj.mname = arr[1];
    obj.lname = arr[2];
}
       
console.log(obj.fname);
console.log(obj.mname); //could be undefined
console.log(obj.lname);