Question

我正在上一门在线课程，但遇到实践问题。我要建立一个bmi（体重指数）计算器，该计算器返回一个值，让用户知道他们的bmi是什么。

我尝试使用if语句解决此问题，但验证程序抛出错误，指出我的解决方案不正确。有人可以看到我的代码有什么问题吗？

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串联在最终输出中添加bmi值

以下是使用模板字符串的方法示例：-

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

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，这是一个简化的解决方案，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'); }

我将.toFixed(2)舍入到两位数字，因为没有人会对13位精度的答案感兴趣。

尽管Math.pow(height,2)在数学上是正确的，但是直接乘积height*height的计算量却大大减少。

（在此示例中无关紧要，但是在您运行多个迭代或在大型数组上工作的情况下，这可能很重要。）

Answer 3

所以我终于能够使它与此一起工作：

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，找出if语句的顺序很重要！

计算bmi并返回字符串的函数

3 个答案: