利用哈希表实现数组的去重以及利用delete批量删除数组元素

//找出多个数组中唯一存在的数字，组成新的数组
function array_diff() {
var hash = {},
arr = [],
midArray = [],
result = [];
for (i in arguments) {
arr = arr.concat(arguments[i]);
}
for (i in arr) {
if (isNaN(hash[arr[i]]) && arr[i] <= "9" && arr[i] >= "0") {
midArray.push(arr[i]);
hash[arr[i]] = midArray.length - 1;
} else if (arr[i] <= "9" && arr[i] >= "0") {
delete midArray[hash[arr[i]]];
}
}
for (i in midArray) {
result.push(midArray[i]);
}
return result;
}

//测试array_diff函数
var a = [1, 2, 3, "a"];
var b = [2, 3, 4, "b"];
var c = [3, 4, 5, "d"];
alert("["+array_diff(a, b, c)+"]") //输出[1,5]