我无法弄清楚此javascript代码中的“未定义”

Question

我唯一的console.log返回未定义。我不知道为什么。

我尝试测试每个代码段，但对于任何特定代码段都不会得到相同的消息。

    let employeeProfile = 
     {name: "Karen King",
      age: 35,
      email: "karen@gmail.com",
      position: "assistant manager",
      beenAssistBefore: true,
      yearsExperience: 2.5,
      mastersDegree: true,
     }

    let $experience1;
    let $experience2;
    let $experience3 = 10000;
    let $baseSalary = 55000;

    function experienceCal(employeeProfile){
      if(employeeProfile.beenAssistBefore == true && 
       employeeProfile.mastersDegree == true){
    $experience1 = (employeeProfile.yearsExperience * 9500) + 
     ($experience3 + $baseSalary);
    return $experience1;

     }else if(employeeProfile.beenAssistBefore == true && 
      employeeProfile.mastersDegree == false){
       $experience2 = (employeeProfile.yearsExperience * 9500) + 
      $baseSalary;
    return $experience2;

    }else if(employeeProfile.beenAssistBefore == false && 
     employeeProfile.mastersDegree == true){
    return $experience3 + $baseSalary; 
    }
    else{
    return $baseSalary;
    }
    }

    function salaryEstimator(employeeProfile){
     if(employeeProfile.position == "assistant manager"){
    experienceCal(employeeProfile);
    }else 
     {alert("This position is not currently available.")
     }
    }
    let myEstimate = salaryEstimator(employeeProfile)
    console.log(myEstimate);

我希望console.log能够打印出该员工的薪水。相反，我得不到定义