递归函数循环通过obj道具无法正常工作

Question

为什么这只会提醒1？

function test() {
 var myobj = {
  a : '1st level prop',
  b : 'findme',
  c : {
    aa : '2nd level prop',
    bb : 'findme',
    cc : {
     aaa : '3rd level prop',
     bbb : 'findme'
    }
   }
 }
 function countem(needle,haystack) {
  var count = count || 0;
  for(var i in haystack) {
   if (typeof(haystack[i]) == 'object') {
    countem(needle,haystack[i]); 
   } else {
    if (needle == haystack[i]) {
     count++; 
    }
   }
  }
  return count;
 }
 alert(countem('findme',myobj));
}

Answer 1

您忘记在递归调用中添加计数。

function test() {
 var myobj = {
  a : '1st level prop',
  b : 'findme',
  c : {
    aa : '2nd level prop',
    bb : 'findme',
    cc : {
     aaa : '3rd level prop',
     bbb : 'findme'
    }
   }
 }
 function countem(needle,haystack) {
  var count = 0;
  for(var i in haystack) {
   if (typeof(haystack[i]) == 'object') {
    count = count + countem(needle,haystack[i]); 
   } else {
    if (needle == haystack[i]) {
     count++; 
    }
   }
  }
  return count;
 }
 alert(countem('findme',myobj));
}

Answer 2

因为您在每次调用count时重置countem。

if (typeof(haystack[i]) == 'object') {
    count += countem(needle,haystack[i]);
}