const arr = ['javascript', 'php', 'python', 'c', 'c#'];
const fromIndex = arr.indexOf('php');
const toIndex = 3;
const element = arr.splice(fromIndex, 1)[0];
arr.splice(toIndex, 0, element);
console.log(arr);
/*
run:
["javascript", "python", "c", "php", "c#"]
*/