循环函数的返回值 [英] Return value from recurring function

问题描述

这个 Meteor 服务器递归方法 commonHint 返回 result undefined 到控制台，即使 finalRes 有一个值.
关于如何将 finalRes 返回给调用者的任何建议?谢谢

This Meteor server recursive method commonHint returns result undefined to the console even the finalRes has a value.
Any suggestion on how to return the finalRes to the caller? thx

  //call the recursive method
  let result = this.commonHint(myCollection.findOne({age: 44}), shortMatches);
        console.log('got most common hint: ' + result); // <=== undefined ====

  'commonHint': function (doc, shortMatches, hinters, results = []) {
      // first call only first 2 args are defined,
      if (!hinters) {
        hinters = [...lib.getCombinations(['arg1', 'arg2', 'arg3'], 2, 3)];
        this.commonHint(doc, shortMatches, hinters, results);  // hinters is an array of length 3 with 2 elements each
        return;
      }

      // get an element from hinters, use its 2 hinters and remove that element from the hinters
      let hintersToUse = hinters.pop();
      let hinter1 = this.cleanMatchItem(hintersToUse[0]);
      let hinter2 = this.cleanMatchItem(hintersToUse[1]);
      let intersect = _.intersection(hinter1, hinter2);

      // which item of the shortMatches best matches with the intersect
      let tempCol = new Meteor.Collection();
      for (let i = 0; i < shortMatches.length; i++) { tempCol.insert({match: shortMatches[i]}); }
      results.push(mostSimilarString(tempCol.find({}), 'match', intersect.join(' ')));

      if (hinters.length > 0) {
        this.commonHint(doc, shortMatches, hinters, results);
      } else {
        let finalRes = lib.mostCommon(results);
        console.log(finalRes);  //<==== has a value
        return finalRes;        //<==== so return it to caller
      }
    },

推荐答案

递归函数中返回结果的每个路径必须返回一个结果.在您的路径中，您有不提供的路径:当未提供 hinters 时，以及当 hinters.length >0 为真.

Every path out of a recursive function that returns a result must return a result. In yours, you have paths that don't: When hinters isn't provided, and when hinters.length > 0 is true.

你应该返回递归调用的结果:

You should return the result of the recursive call:

  if (!hinters) {
    hinters = [...lib.getCombinations(['arg1', 'arg2', 'arg3'], 2, 3)];
    return this.commonHint(doc, shortMatches, hinters, results);  // hinters is an array of length 3 with 2 elements each
//  ^^^^^^
  }

  // ...

  if (hinters.length > 0) {
    return this.commonHint(doc, shortMatches, hinters, results);
//  ^^^^^^
  } else {
    let finalRes = lib.mostCommon(results);
    console.log(finalRes);  //<==== has a value
    return finalRes;        //<==== so return it to caller
  }

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