Temperature conversion program Javascript-Front-end Q&A-php.cn

With the rapid development of science and technology, the writing of computer programs has become an indispensable part of people's lives. The temperature conversion program is a small program commonly used in life. It can convert Celsius temperature into Fahrenheit temperature, or Fahrenheit temperature into Celsius temperature. In this article, we will introduce a temperature conversion program written in Javascript to help people perform temperature conversion more conveniently.

Before you start writing the program, you first need to clarify the conversion formula between Celsius and Fahrenheit temperatures. The conversion of temperature units is performed by the following formula:

Fahrenheit = Celsius × 1.8 32

Celsius = (Fahrenheit - 32) ÷ 1.8

Understand Now that we have the formula, we can start writing the program.

First, we need to add a form to the HTML file for entering the temperature value and selecting the temperature unit. The code is as follows:

<form>
  <label>输入温度：</label>
  <input type="number" id="temperature">

  <label>选择温度单位：</label>
  <select id="unit">
    <option value="celsius">摄氏度</option>
    <option value="fahrenheit">华氏度</option>
  </select>

  <button type="button" onclick="convertTemperature()">转换</button>

  <div id="result"></div>
</form>

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This form contains an input box, a drop-down box and a button. The input box is used to enter the temperature value, the drop-down box is used to select the temperature unit, and the button is used to trigger the conversion function. After the conversion is completed, the conversion results will be displayed in the

tag.

Next, we need to write Javascript code to complete the conversion process. The code is as follows:

<script>
  function convertTemperature() {
    // 获取用户输入的数值和单位
    var temperature = document.getElementById("temperature").value;
    var unit = document.getElementById("unit").value;

    // 如果输入为空，则提示用户输入数字
    if (isNaN(temperature)) {
      document.getElementById("result").innerHTML = "请输入数字!";
      return;
    }

    // 根据选择的单位进行温度转换
    if (unit === "celsius") {
      var fahrenheit = temperature * 1.8 + 32;
      document.getElementById("result").innerHTML = temperature + "摄氏度 = " + fahrenheit + "华氏度";
    } else {
      var celsius = (temperature - 32) / 1.8;
      document.getElementById("result").innerHTML = temperature + "华氏度 = " + celsius + "摄氏度";
    }
  }

</script>

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First, we define a function called convertTemperature, in which the temperature value and temperature unit input by the user are obtained. Then, we used an if statement to determine whether the user entered a number. If the user input is not a number, use innerHTML to display the prompt information in the

tag and exit the function. If the user enters a number, it is converted according to the selected temperature unit and the result is displayed in a

tag.

At this point, our temperature conversion program is complete and can be run on any browser that supports Javascript. Users can easily complete temperature conversions by simply entering numbers and selecting temperature units.

Finally, it should be noted that this program is just a simple example program, and there are many places that can be improved. For example, you can increase the handling of user input errors or optimize the layout of the interface. In any case, the method of writing a temperature conversion program in Javascript is very simple and easy to understand. I hope this article can help readers better understand the Javascript language.

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