SOURCE

const array = [1,2,3,4,21,34,2,1,23,4,5];
/* 第一种 */
console.log([...new Set(array)])

/*第二种*/
function distinct(arr){
	const newArr = [];
	for(let i = 0; i < arr.length; i++){
		const crr = arr[i];
		if(!(newArr.includes(crr))){
			newArr.push(crr)
		}
	}
	return newArr
}
console.log(distinct(array))

<h1>数组去重</h1>