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📜  JavaScript 中的货币转换器

📅  最后修改于: 2021-11-07 08:35:36             🧑  作者: Mango

在本文中，我们将实现一个货币转换器，它可以简单地将货币转换为任何其他国家的货币。

先决条件：

  • 基本的 HTML、CSS、JavaScript 。

方法：

  • HTML 代码是为 GUI 实现的，用于用户输入金额和两种货币。
  • 选择货币，转换按钮显示转换的金额。
  • 重置按钮重置数据。
  • JavaScript 函数和自定义方法用于实现货币转换，如 addEventListener()。
  • 脚本文件中使用了货币兑换 API。

HTML 代码：以下 HTML 代码为用户条目（如金额和需要转换的货币）实现了 GUI。

index.html


  

    
    
    
  
    Currency Converter
  
    
    
    
    
  
    
    
  
    
    

  

  
    
    

        Currency Converter

  
    

    

  
        

  
            

                
                
            

  
            

                

                    

                        

                            From
                        

                        
                    

                

  
                

                    

                        

                            To
                        

                        
                    

                

            

  
            

  
                
                
  
                
                
            

  
        

  
        

  
            
            
Converted Amount :
                
           
            

        

    

  
    
    

  

style.css
body {
    background-color: aliceblue;
    background-position: center;
    background-size: cover;
    background-attachment: fixed;
    background-repeat: no-repeat;
}
  
.heading {
    font-family: 'Pacifico', cursive;
    margin: 35px auto 20px;
}
  
hr {
    border-top: 2px solid black;
    width: 40%;
    margin-bottom: 55px;
}
  
.main {
    width: 50vw;
    margin: auto;
    padding: 30px;
    border-radius: 5px;
    background-color: rgba(0, 0, 0, 0.5);
    color: white;
}
  
label {
    font-size: 20px;
}
  
.btn {
    width: 200px;
}
  
#finalAmount {
    font-family: 'Lobster', cursive;
    display: none;
    margin: 50px auto;
}
  
#finalAmount h2 {
    font-size: 50px;
}
  
.finalValue {
    font-family: 'Amiri', serif;
}
  
@media (max-width: 768px) {
    hr {
        width: 60%;
    }
    .main {
        width: 100%;
    }
}
  
@media (max-width: 400px) {
    .heading {
        font-size: 60px;
    }
    hr {
        width: 75%;
    }
    #finalAmount h2, .finalValue {
        font-size: 40px;
    }
}

Javascript
// include api for currency change
const api = "https://api.exchangerate-api.com/v4/latest/USD";
  
// for selecting different controls
var search = document.querySelector(".searchBox");
var convert = document.querySelector(".convert");
var fromCurrecy = document.querySelector(".from");
var toCurrecy = document.querySelector(".to");
var finalValue = document.querySelector(".finalValue");
var finalAmount = document.getElementById("finalAmount");
var resultFrom;
var resultTo;
var searchValue;
  
// Event when currency is changed
fromCurrecy.addEventListener('change', (event) => {
    resultFrom = `${event.target.value}`;
});
  
// Event when currency is changed
toCurrecy.addEventListener('change', (event) => {
    resultTo = `${event.target.value}`;
});
  
search.addEventListener('input', updateValue);
  
// function for updating value
function updateValue(e) {
    searchValue = e.target.value;
}
  
// when user clicks, it calls function getresults 
convert.addEventListener("click", getResults);
  
// function getresults
function getResults() {
    fetch(`${api}`)
        .then(currency => {
            return currency.json();
        }).then(displayResults);
}
  
// display results after convertion
function displayResults(currency) {
    let fromRate = currency.rates[resultFrom];
    let toRate = currency.rates[resultTo];
    finalValue.innerHTML = 
       ((toRate / fromRate) * searchValue).toFixed(2);
    finalAmount.style.display = "block";
}
  
// when user click on reset button
function clearVal() {
    window.location.reload();
    document.getElementsByClassName("finalValue").innerHTML = "";
};

CSS 代码：以下是上述 HTML 文件中使用的文件“style.css”的内容。

样式文件

body {
    background-color: aliceblue;
    background-position: center;
    background-size: cover;
    background-attachment: fixed;
    background-repeat: no-repeat;
}
  
.heading {
    font-family: 'Pacifico', cursive;
    margin: 35px auto 20px;
}
  
hr {
    border-top: 2px solid black;
    width: 40%;
    margin-bottom: 55px;
}
  
.main {
    width: 50vw;
    margin: auto;
    padding: 30px;
    border-radius: 5px;
    background-color: rgba(0, 0, 0, 0.5);
    color: white;
}
  
label {
    font-size: 20px;
}
  
.btn {
    width: 200px;
}
  
#finalAmount {
    font-family: 'Lobster', cursive;
    display: none;
    margin: 50px auto;
}
  
#finalAmount h2 {
    font-size: 50px;
}
  
.finalValue {
    font-family: 'Amiri', serif;
}
  
@media (max-width: 768px) {
    hr {
        width: 60%;
    }
    .main {
        width: 100%;
    }
}
  
@media (max-width: 400px) {
    .heading {
        font-size: 60px;
    }
    hr {
        width: 75%;
    }
    #finalAmount h2, .finalValue {
        font-size: 40px;
    }
}

JavaScript 代码：以下是上述 HTML 代码中使用的文件“script.js”的内容。

Javascript 

// include api for currency change
const api = "https://api.exchangerate-api.com/v4/latest/USD";
  
// for selecting different controls
var search = document.querySelector(".searchBox");
var convert = document.querySelector(".convert");
var fromCurrecy = document.querySelector(".from");
var toCurrecy = document.querySelector(".to");
var finalValue = document.querySelector(".finalValue");
var finalAmount = document.getElementById("finalAmount");
var resultFrom;
var resultTo;
var searchValue;
  
// Event when currency is changed
fromCurrecy.addEventListener('change', (event) => {
    resultFrom = `${event.target.value}`;
});
  
// Event when currency is changed
toCurrecy.addEventListener('change', (event) => {
    resultTo = `${event.target.value}`;
});
  
search.addEventListener('input', updateValue);
  
// function for updating value
function updateValue(e) {
    searchValue = e.target.value;
}
  
// when user clicks, it calls function getresults 
convert.addEventListener("click", getResults);
  
// function getresults
function getResults() {
    fetch(`${api}`)
        .then(currency => {
            return currency.json();
        }).then(displayResults);
}
  
// display results after convertion
function displayResults(currency) {
    let fromRate = currency.rates[resultFrom];
    let toRate = currency.rates[resultTo];
    finalValue.innerHTML = 
       ((toRate / fromRate) * searchValue).toFixed(2);
    finalAmount.style.display = "block";
}
  
// when user click on reset button
function clearVal() {
    window.location.reload();
    document.getElementsByClassName("finalValue").innerHTML = "";
};

输出：

  • 点击前：

  • 点击后：

转换后