两个有序数组合并并且去重

var arr1 = [1,2,3,4,5,5,6,6,7];
var arr2 = [2,3,4,4,5,6,8,8,9,10,11];
function mergeArr(arr1,arr2){
    var i = 0, j = 0;
    var res = [];
    while(i < arr1.length && j < arr2.length){
        if(arr1[i] < arr2[j]){
            //注意这里的判断条件，如果res为空时，length-1会越界
            //因为res也是有序的数组，所以只需要跟它最后一个元素比较就可以知道是否有重复
            if(res.length === 0 || res[res.length-1] !== arr1[i]){
                res.push(arr1[i]);
            }
            //注意不管有没有重复都会++；j同理
            i++;
        }else{
            if(res.length === 0 || res[res.length-1] !== arr2[j]){
                res.push(arr2[j]);
            }
            j++;
        }
    }
    while(i < arr1.length){
        if(res.length === 0 || res[res.length-1] !== arr1[i]){
            res.push(arr1[i]);
        }
        i++;
    }
    while(j < arr2.length){
        if(res.length === 0 || res[res.length-1] !== arr2[j]){
            res.push(arr2[j]);
        }
        j++;
    }
    console.log(res);
    return res;
}
mergeArr(arr1,arr2);