let str = "java go c node.js c++ python";
let pos = str.lastIndexOf("c");
let part1 = "", part2 = "";
if (pos !== -1) {
part1 = str.substring(0, pos);
part2 = str.substring(pos);
}
console.log(part1);
console.log(part2);
/*
run:
java go c node.js
c++ python
*/