从二进制搜索函数中返回值

Question

以下代码对数组进行二进制搜索。我做了很多部分并且让代码在理论上工作;不幸的是，我无法从函数中返回值;

简而言之，我想要'len'被退回;如果在该行中设置断点，您将看到'len'包含正确的答案。但我错过了一些非常愚蠢的事情。请帮我识别一下。

var states = ['Alabama','Alaska','American Samoa','Arizona','Arkansas','California','Colorado','Connecticut','Delaware','District of Columbia','Federated States of Micronesia','Florida','Georgia','Guam','Hawaii','Idaho','Illinois','Indiana','Iowa','Kansas','Kentucky','Louisiana','Maine','Marshall Islands','Maryland','Massachusetts','Michigan','Minnesota','Mississippi','Missouri','Montana','Nebraska','Nevada','New Hampshire','New Jersey','New Mexico','New York','North Carolina','North Dakota','Northern Mariana Islands','Ohio','Oklahoma','Oregon','Palau','Pennsylvania','Puerto Rico','Rhode Island','South Carolina','South Dakota','Tennessee','Texas','Utah','Vermont','Virgin Island','Virginia','Washington','West Virginia','Wisconsin','Wyoming'];
function binarySearch(arr1,term){
  var arr = [...arr1],
    len = 0;
  function helper(arr,term) {
    if(arr.length > 1) {
      if(arr[Math.floor(arr.length/2)] === term) {
          len += Math.floor(arr.length/2);
          return len;
      }
      if(arr[Math.floor(arr.length/2)] < term) {
          len += Math.floor(arr.length/2);
          arr.splice(0,Math.floor(arr.length/2));
          helper(arr,term)
      }
      else if (arr[Math.floor(arr.length/2)] > term) {
          arr.splice(Math.floor(arr.length/2),arr.length-1);
          helper(arr,term)
      }
    } else {
        return 'Element not found';
    }
  }
  return helper(arr,term);
}
console.log(binarySearch(states,"Arizona"));

Answer 1

您的递归调用也应该返回给调用者：

更换：

helper(arr,term)

有：

return helper(arr,term)

在这两种情况下。