返回值未定义

我在尝试从函数调用获取数组时遇到了一些困惑。我不知道为什么返回的是未定义的值,而不是预期值。

以下内容按预期记录阵列。

findFraudByFromID = (fraudID) => {
  this.KYCinstance.getPastEvents('ReportedFraud',{
  filter: {fromID: fraudID},
  fromBlock: 0
  }, (error, events) => {
    var frauds = [];
    for (var i = 0; i < events.length; i++) {
      frauds.push(events[i].returnValues.fraudID); 
    }
    console.log(frauds);
  })
} 

trackFraud = (fraudID) => {

  findFraudByFromID.call(this, 1);

}

以下日志 undefined

findFraudByFromID = (fraudID) => {
  this.KYCinstance.getPastEvents('ReportedFraud',{
  filter: {fromID: fraudID},
  fromBlock: 0
  }, (error, events) => {
    var frauds = [];
    for (var i = 0; i < events.length; i++) {
      frauds.push(events[i].returnValues.fraudID); 
    }
    return frauds;
  })
} 

trackFraud = (fraudID) => {
  frauds = findFraudByFromID.call(this, 1);
  console.log(frauds);
}