函数计算bmi并返回字符串

Question

我正在上一门在线课程，在这门课上我遇到了一道练习题。我要建立一个bmi (身体质量指数)计算器，它返回一个值，让用户知道他们的bmi是什么。

我尝试使用if语句来解决这个问题，但是验证器抛出一个错误，指出我的解决方案不正确。有人能看到我的代码可能出了什么问题吗？

var interpretation = "";

function bmiCalculator (weight, height) {
    bmi = weight / Math.pow(height, 2);

    if (bmi < 18.5) {
        interpretation = "Your BMI is " + bmi + ", so you are underweight";
    } else if (bmi => 18.5 && bmi <= 24.9) {
        interpretation = "Your BMI is " + bmi +", so you have a normal weight";
    } else {
        interpretation = "Your BMI is " + bmi + ", so you are overweight";
    }

   return interpretation;
}

Answer 1

您需要使用模板字符串或字符串连接在最终输出中添加bmi值

这里有一个使用模板字符串的示例:-

var interpretation = "";

function bmiCalculator(weight, height) {
    bmi = weight / Math.pow(height, 2);

    if (bmi < 18.5) {
        interpretation = `Your BMI is ${bmi}, so you are underweight`;
    } else if (bmi >= 18.5 && bmi <= 24.9) {
        interpretation = `Your BMI is ${bmi}, so you have a normal weight`;
    } else {
        interpretation = `Your BMI is ${bmi}, so you are overweight`;
    }

    return interpretation;
}

您的代码可以进一步改进到这一点

function bmiCalculator(weight, height) {
    let bmi = weight / Math.pow(height, 2);
    let interpretation = `Your BMI is ${bmi}, so you `
    if (bmi < 18.5) {
        interpretation += `are underweight`;
    } else if (bmi < 25) {
        interpretation += `have a normal weight`;
    } else {
        interpretation += `are overweight`;
    }

    return interpretation;
}

Answer 2

总结上面的评论，这里是一个简化的解决方案，它将做同样的事情：

function calc(weight, height) { 
  var bmi = weight/(height*height);
  var bmis=bmi.toFixed(2);
  return `Your BMI is ${bmis}, so you `+
       (bmi<18.5?'are underweight'
      : bmi<25  ?'have a normal weight'
      :          'are overweight'); }

我使用.toFixed(2)将四舍五入添加到两位数，因为没有人会对13位精度的答案感兴趣。

虽然Math.pow(height,2)在数学上是正确的，但直接乘积height*height的计算要容易得多。

(在本例中这并不重要，但在运行多次迭代或处理大型数组的情况下，这一点可能很重要。)

Answer 3

所以我终于能够让它用这个来工作：

function bmiCalculator (weight, height) {
    var bmi = weight/(height*height);
    if (bmi > 24.9){
        return "Your BMI is " + bmi + ", so you are overweight.";
    }
    if (bmi >= 18.5 && bmi <=24.9){
        return "Your BMI is " + bmi + ", so you have a normal weight.";
    }
    if (bmi < 18.5){
        return "Your BMI is " + bmi + ", so you are underweight.";
    }
}

在这种情况下，if语句的顺序非常重要！