set去重

var oldArr=[2,3,4,3,4,5,6,2,1,2,34,5]
var newArr=[...new Set(oldArr)]
console.log(newArr)

indexOf去重

var oldArr=[2,3,4,3,4,5,6,2,1,2,34,5]
var newArr=[]
for(var i=0;i<oldArr.length;i++){
    oldArr[i].index=i
    if(newArr.indexOf(oldArr[i])==-1){
        newArr.push(oldArr[i])
    }
}
console.log(newArr)

splice去重

var arr = [11, 0, 345, 0, 0, 43, 345, 11, 43]

	for (var i = 0; i <= arr.length; i++) {
		for (var j = j + 1; j <= arr.length; j++) {
			if (arr[i] == arr[j]) {
				arr.splice(j, 1);
				j--
			}
		}
	}