HTML中的JS代码，用于计算平方面积。包括所有形状的面积，公式= 2 *（a * b + a * c + b * c）

Question

我有这个JavaScript代码，可以计算4种形状的区域。

我只需要用此公式2 * (a*b + a*c + b*c)实现如何计算SQUARE的面积。

我尝试过自己，但未显示任何输出。

function calculateArea() {

    // get the selected shape
    let shape = document.getElementById("id_shapes").value;

    // calculate the shape's area
    let area = 0;
    switch (shape) {
        case "circle":
            let radius = document.getElementById("id_radius").value;
            area = Math.PI * radius * radius;
            break;
        case "triangle":
            let base = document.getElementById("id_base").value;
            let height = document.getElementById("id_height").value;
            area = base * height / 2;
            break;
        **case "square":
            let side = document.getElementById("id_side").value;
            area = side * side;**
            break;
        case "rectangle":
            let length = document.getElementById("id_length").value;
            let width = document.getElementById("id_width").value;
            area = length * width;
            break;
}

// output the area
document.getElementById("id_output").innerHTML = "Area = " + area;

Answer 1

js的正确代码应该是这样：

let area = 0;

function calculateArea() {
  // get the selected shape
  let shape = document.getElementById("id_shapes").value;
  // calculate the shape's area
  switch (shape) {
    case "circle":
      let radius = document.getElementById("id_radius").value;
      area = Math.PI * radius * radius;
      break;
    case "triangle":
      let base = document.getElementById("id_base").value;
      let height = document.getElementById("id_height").value;
      area = (base * height) / 2;
      break;
    case "square":
      let side = document.getElementById("id_side").value;
      area = side * side;
      break;
    case "rectangle":
      let length = document.getElementById("id_length").value;
      let width = document.getElementById("id_width").value;
      area = length * width;
      break;
  }
  document.getElementById("id_output").innerHTML = "Area = " + area;
}