js implements a simple calculator

Use native js to implement a simple calculator (with detailed comments) for your reference. The specific contents are as follows

<!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:

<script>
      // Get all elements with class name block var blocks = document.getElementsByClassName("block");
      // Get input
      var input = document.getElementById("input1");
      //Declare the first value var firstValue = 0,
        bool = false;
      //Declare operator var type;
      for (var i = 0; i < blocks.length; i++) {
       //Click on the i-th block
        blocks[i].onclick = function () {
          //This points to whoever is clicked. Here, this points to the element clicked each time console.log(this);
          //this.innerHTML displays the contents of the clicked div (such as 1,2,3,-,+)
          //Judge whether the clicked value is a number (either NaN or a number)
          if (!isNaN(this.innerHTML)) {      
            // bool is initially false. When bool is false, you can continue to input. When bool is true, the input is cleared to 0
            if (bool) {
              input.value = "0";
              bool = false;
            }
            // Add the value in input to the content clicked, and convert it to a number to remove the leading 0, and then convert it to a character input.value = Number(input.value + this.innerHTML).toString();
          } else {
           //Judge whether the click is + - * /if (this.innerHTML !== "C" && this.innerHTML !== "=") {
              //Save the first number to firstValue 
              firstValue = Number(input.value);
              //Store the operator in type
              type = this.innerHTML;
              //Reset the value in input to 0
              input.value = "0";
            } else if (this.innerHTML === "C") { //Judge the situation of clicking C//Reset all firstValue = 0;
              type = undefined;
              input.value = "0";
            } else { //Judge the situation of clicking = //Perform operations according to the type of operator 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 "/":
                  // Reset input.value when the divisor is 0
                  if (Number(input.value) === 0) input.value = "0";
                  else
                    input.value = (firstValue / Number(input.value)).toString();
                  break;
              }
              //When bool is true, after clicking "=", when you enter again, input.value is 0
              bool = true;
            }
          }
        };
      }

The above is the full content of this article. I hope it will be helpful for everyone’s study. I also hope that everyone will support 123WORDPRESS.COM.

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