JavaScript数组去重：从基础遍历到哈希表优化方案

var arr = [1,2,3,4,5,6,1,6,7,2];
var newArr = [];
for(var i =0;i<arr.length-1;i++){
　　 if(newArr.indexOf(arr[i]) == -1){
　　　　newArr.push(arr[i]);
　　}
}

function unique(arr) {
var result = [], isRepeated;
for (var i = 0, len = arr.length; i < len; i++) {
isRepeated = false;
for (var j = 0, len = result.length; j < len; j++) {
if (arr[i] == result[j]) { 
isRepeated = true;
break;
}
}
if (!isRepeated) {
result.push(arr[i]);
}
}
return result;
} 

function unique(arr) {
var result = [], hash = {};
for (var i = 0, elem; (elem = arr[i]) != null; i++) {
if (!hash[elem]) {
result.push(elem);
hash[elem] = true;
}
}
return result;
//http://www.cnblogs.com/sosoft/
}