JS之搜索旋转排序数组

var search = function(nums, target) {
    //凡是从有序数列中寻找目标值，第一个应该想到二分法
    if(nums.length==0)return -1
    if(nums.length==1)return nums[0]===target?0:-1
    let l=0,r=nums.length-1;
    while(l<=r){
        let mid =Math.floor((l+r)/2);
        if(nums[mid]===target)return mid;
        if(nums[mid]>=nums[l]){
            if(target>=nums[l]&&target<=nums[mid]){
                r=mid-1
            }else{
                l=mid+1
            }
        }else{
            if(target<=nums[r]&&target>=nums[mid]){
                l=mid+1
            }else{
                r=mid-1
            }
        }
    }
    return -1

};