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js实现一个简易的计算器

︶ㄣ米米素材网 メ
米米素材网V管理员 / 阅读
0711

这篇文章主要为大家详细介绍了js实现一个简易的计算器，文中示例代码介绍的非常详细，具有一定的参考价值，感兴趣的小伙伴们可以参考一下

利用原生js实现一个简易的计算器（附详细注释），供大家参考，具体内容如下

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<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
    <style>
      .divs {
        width: 500px;
        height: 600px;
        border: 1px solid #000000;
        margin: auto;
      }
      .divs > input {
        width: 460px;
        height: 45px;
        margin-left: 18px;
        margin-top: 10px;
        font-size: 30px;
        background-color: white;
        text-align: right;
      }
      .divs > div {
        width: 100px;
        height: 100px;
        float: left;
        border: 1px solid #000000;
        margin-left: 18px;
        margin-top: 25px;
        font-size: 40px;
        line-height: 100px;
        text-align: center;
        user-select: none;
      }
    </style>
  </head>
  <body>
    <div class="divs">
      <input type="text" value="0" id="input1" disabled />
      <div class="block">7</div>
      <div class="block">8</div>
      <div class="block">9</div>
      <div class="block">-</div>
      <div class="block">4</div>
      <div class="block">5</div>
      <div class="block">6</div>
      <div class="block">+</div>
      <div class="block">1</div>
      <div class="block">2</div>
      <div class="block">3</div>
      <div class="block">*</div>
      <div class="block">C</div>
      <div class="block">0</div>
      <div class="block">=</div>
      <div class="block">/</div>
</div>

js:

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<script>
      // 获取到所有类名为block的元素
      var blocks = document.getElementsByClassName("block");
      // 获取到input
      var input = document.getElementById("input1");
      // 声明第一个数值
      var firstValue = 0,
        bool = false;
      // 声明运算符
      var type;
      for (var i = 0; i < blocks.length; i++) {
       //点击第i个block
        blocks[i].onclick = function () {
          //点击谁，this就指向谁，在这里this指向每次点击的元素
          console.log(this);
          //this.innerHTML显示点击的div里面的内容（比如1,2,3,-,+）
          //判断点击的为数字的情况（不是NaN，就是数字）
          if (!isNaN(this.innerHTML)) {     
            // bool初始为false,当bool为false时,可以不断输入,当bool为true时，input清空为0
            if (bool) {
              input.value = "0";
              bool = false;
            }
            // 将input中的value累加点击的内容，将它强转为数字是为了去掉最前面的0，最后再转为字符
            input.value = Number(input.value + this.innerHTML).toString();
          } else {
           //判断点击为+ - * /的情况
            if (this.innerHTML !== "C" && this.innerHTML !== "=") {
              //将第一个数存到firstValue
              firstValue = Number(input.value);
              //将运算符存到type
              type = this.innerHTML;
              //将input中的value重置为0
              input.value = "0";
            } else if (this.innerHTML === "C") {  //判断点击C的情况
              // 全都重置
              firstValue = 0;
              type = undefined;
              input.value = "0";
            } else {  //判断点击=的情况
              //根据运算符的类型进行运算
              switch (type) {
                case "+":
                  input.value = (firstValue + Number(input.value)).toString();
                  break;
                case "-":
                  input.value = (firstValue - Number(input.value)).toString();
                  break;
                case "*":
                  input.value = (firstValue * Number(input.value)).toString();
                  break;
                case "/":
                  // 除数为0时重置input.value
                  if (Number(input.value) === 0) input.value = "0";
                  else
                    input.value = (firstValue / Number(input.value)).toString();
                  break;
              }
              //bool为true时，点击"="后,当再次输入时，input.value为0
              bool = true;
            }
          }
        };
      }

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原文链接：https://blog.csdn.net/nqq0921/article/details/115536722