function binarySerach(arr,val,leftIndex,RightIndex){
var mid = Math.floor((leftIndex+RightIndex)/2);
var midVal = arr[mid];
if(midVal>val){
binarySerach(arr,val,leftIndex,mid);
console.log("在左边");
}else if(midVal<val){
binarySerach(arr,val,mid,RightIndex);
console.log("在右边");
}else{
console.log("找到了，下标为"+mid);
}
}
var arr=[0,1,2,3,4,5,6,7,8,9,10];
binarySerach(arr,7,0,arr.length-1);
//找到了，下标为7
