var testingArray = [];
for (let i=0, ii=40000; i<ii; i++) {
testingArray.push(Math.round(Math.random() * ii))
}
testingArray.filter((currentValue, index, arr) => arr.indexOf(currentValue) === index)
testingArray.reduce((accumulator, currentValue) => (
accumulator.includes(currentValue) ? accumulator : [...accumulator, currentValue]
), []);
[...new Set(testingArray)];