编辑代码

let arr = [1, 25, 34, 66, 117, 158, 169, 200, 222, 258, 269, 279, 300];
function getIndex(target, arr) {
    let low = 0;
    let high = arr.length -1;
    while(low<=high){
        let mid = Math.floor((low + high) / 2);
        if(target === arr[mid]){
            return target;
        }else if(target < arr[mid] && target >= arr[mid - 1]){
            return arr[mid - 1];
        }else if(target > arr[mid]){
            low = mid + 1;
        }else if(target < arr[mid]) {
            high = mid - 1;
        }
    }
    return arr[arr.length - 1];
}
console.log(getIndex(250, arr));