How to create and download CSV files in JavaScript?-JS Tutorial-php.cn

Home

Web Front-end

JS Tutorial

How to create and download CSV files in JavaScript?

王林

Sep 17, 2023 am 08:09 AM

如何在 JavaScript 中创建和下载 CSV 文件？

JavaScript has powerful capabilities to manipulate various data and handle files in different formats. Sometimes, developers need to process data using CSV files while developing web applications using JavaScript.

For example, we are building an e-commerce platform where users can buy and sell products. Additionally, we want to allow users to download order details into a CSV file based on a time range. In this case, we need to interact with the data and the CSV file. Another example is that online banking websites allow us to download transaction details in a CSV file.

In this tutorial, we will learn to create a csv file based on the given data in JavaScript or JSON object format and download the file.

grammar

Users can create and download CSV files from given data by following the following syntax.

laptops.forEach(function (row) {
   csvData += data
});

let anchor = document.createElement('a');
anchor.href = 'data:text/csv;charset=utf-8,' + encodeURI(csvData);
anchor.click();

In the above syntax, "csvData" is an array appending the CSV file rows with data. After that, we create a CSV file from csvData using anchor tags and download the file by clicking on the anchor element.

Example

In the following example, we first create an array of objects named "laptops", where each object of the array contains the brand, processor, price, and RAM properties.

In the downloadFile() function, we add the comma separated object keys to the "csvData" variable. After that, we loop through the given array of objects and prepare a single row by concatenating each attribute value in the same order (separated by commas and appending it to the "CSVData" variable).

Next, we create the anchor element using the createElement() method and add "csvData" as the value of the href attribute after encoding using the encodeURI() method. Additionally, we set the target value and download attribute value. Finally, we click on the anchor element to download the CSV file.

In the output, the user can click a button to download the data to a CSV file.

<html>
<body>
   <h3 id="Creating-and-dowlonading-the-CSV-file-from-the-given-data-in-JavaScript">Creating and dowlonading the CSV file from the given data in JavaScript</h3>
   <div id="data"> </div>
   <button onclick="downloadFile()"> Download CSV file </button>
   <script>
      let laptops = [{
         brand: 'HP',
         processor: 'i3',
         price: 30000,
         ram: 4
      },
      {
         brand: 'Dell',
         processor: 'i5',
         price: 50000,
         ram: 8
      },
      {
         brand: 'Apple',
         processor: 'i7',
         price: 70000,
         ram: 16
      },
      {
         brand: 'Lenovo',
         processor: 'i3',
         price: 35000,
         ram: 4
      },
      {
         brand: 'Asus',
         processor: 'i5',
         price: 45000,
         ram: 8
      },
      {
         brand: 'Acer',
         processor: 'i7',
         price: 65000,
         ram: 16
      }
      ];
   
      // Function to download data to a CSV file
      function downloadFile() {
      
         // Add header
         let csvData = 'Brand, Processor, Price, RAM';
         
         // Add data
         laptops.forEach(function (row) {
            csvData += row.brand + ',' + row.processor + ',' + row.price + ',' + row.ram + '';
         });
         
         // Download the CSV file
         let anchor = document.createElement('a');
         anchor.href = 'data:text/csv;charset=utf-8,' + encodeURI(csvData);
         anchor.target = '_blank';
         anchor.download = 'laptops.csv';
         anchor.click();
      }
   </script>
</body>
</html>

Example

In the example below, we will get the data from the API and create a CSV file using the JSON data. We have created a button in the HTML section and when the user clicks on the button, it executes the downloadFile() function to get the JSON data and download it into a CSV file.

Programmers can follow the following steps to understand the sample code -

Step 1 - Use the fetch() API to get data from the API URL.

Step 2 - After that, convert the response into a JSON object using the res.json() method.

Step 3 - In the then() block, initialize the csvData[] array to store the rows of the CSV file.

Step 4 - Get the first object from the response and pass it as argument to the Object.keys() method to get all the keys in the array. After that, use the join() method to concatenate the keys into a single string, separated by commas and push to the csvData array.

Step 5 - Loop through all the objects we got in the response. In the loop, we use the map() method with the 'heads' array to get the value from the current object based on the 'heads' array element (object key) and map the value to the 'rowValues' array.

Step 6 - Next, use the join() method to join all the elements of the "rowValues" array and push them into the "csvData" array.

Step 7 - Concatenate all the elements of the "csvData" array using the "

" delimiter and pass it as getCSVFile() function parameter.

Step 8 - In the getCSVFile() function, create a new instance of the anchor element. After that, set the encoded csvData to the 'href' attribute value and set the 'target' and 'download' attribute values.

Step 9- Click on the anchor element to download the file.

<html>
<body>
   <h3 id="Creating-and-dowlonading-the-CSV-file-i-after-fetching-JSON-data-in-JavaScript">Creating and dowlonading the CSV file </i> after fetching JSON data in JavaScript</h3>
   <div id = "data"> </div>
   <button onclick = "downloadFile()"> Download CSV file </button>
   <script>
      function downloadFile() {
         let APIURL = "https://dummyjson.com/products";
         
         // Fetch data from API
         fetch(APIURL)
         .then(response => response.json())
         .then(data => {
            let csvData = [];
            
            // Get headers
            let heads = Object.keys(data.products[0]);
            
            // Add headers to csvData
            csvData.push(heads.join(','));
            
            // Traveres through each row
            for (let row of data.products) {
               
               // Get values from each row
               let rowValues = heads.map(headerData => {
                  
                  // Get value according to the header
                  let final = ('' + row[headerData]).replace(/"/g, '"');
                  return `"${final}"`;
               });
               
               // Push values in csvData
               csvData.push(rowValues.join(','));
            }
            // Call function to download CSV file
            getCSVFile(csvData.join(''));
         });
      }
      function getCSVFile(csvData) {
         let anchor = document.createElement('a');
         anchor.href = 'data:text/csv;charset=utf-8,' + encodeURI(csvData);
         anchor.target = '_blank';
         anchor.download = 'test.csv';
         anchor.click();
      }
   </script>
</body>
</html>

Both sample codes contain two main parts. The first part is to manipulate the given data and concatenate them with a comma separated string, which we will use for the CSV file data. The next part is to append the data to the file and download the file. To create a CSV file, we use a dummy instance of the anchor element.

The above is the detailed content of How to create and download CSV files in JavaScript?. For more information, please follow other related articles on the PHP Chinese website!

Statement

This article is reproduced at:tutorialspoint. If there is any infringement, please contact admin@php.cn delete

Replace String Characters in JavaScriptMar 11, 2025 am 12:07 AM

Detailed explanation of JavaScript string replacement method and FAQ This article will explore two ways to replace string characters in JavaScript: internal JavaScript code and internal HTML for web pages. Replace string inside JavaScript code The most direct way is to use the replace() method: str = str.replace("find","replace"); This method replaces only the first match. To replace all matches, use a regular expression and add the global flag g: str = str.replace(/fi

Build Your Own AJAX Web ApplicationsMar 09, 2025 am 12:11 AM

So here you are, ready to learn all about this thing called AJAX. But, what exactly is it? The term AJAX refers to a loose grouping of technologies that are used to create dynamic, interactive web content. The term AJAX, originally coined by Jesse J

10 jQuery Fun and Games PluginsMar 08, 2025 am 12:42 AM

10 fun jQuery game plugins to make your website more attractive and enhance user stickiness! While Flash is still the best software for developing casual web games, jQuery can also create surprising effects, and while not comparable to pure action Flash games, in some cases you can also have unexpected fun in your browser. jQuery tic toe game The "Hello world" of game programming now has a jQuery version. Source code jQuery Crazy Word Composition Game This is a fill-in-the-blank game, and it can produce some weird results due to not knowing the context of the word. Source code jQuery mine sweeping game

How do I create and publish my own JavaScript libraries?Mar 18, 2025 pm 03:12 PM

Article discusses creating, publishing, and maintaining JavaScript libraries, focusing on planning, development, testing, documentation, and promotion strategies.

jQuery Parallax Tutorial - Animated Header BackgroundMar 08, 2025 am 12:39 AM

This tutorial demonstrates how to create a captivating parallax background effect using jQuery. We'll build a header banner with layered images that create a stunning visual depth. The updated plugin works with jQuery 1.6.4 and later. Download the

How do I optimize JavaScript code for performance in the browser?Mar 18, 2025 pm 03:14 PM

The article discusses strategies for optimizing JavaScript performance in browsers, focusing on reducing execution time and minimizing impact on page load speed.

Getting Started With Matter.js: IntroductionMar 08, 2025 am 12:53 AM

Matter.js is a 2D rigid body physics engine written in JavaScript. This library can help you easily simulate 2D physics in your browser. It provides many features, such as the ability to create rigid bodies and assign physical properties such as mass, area, or density. You can also simulate different types of collisions and forces, such as gravity friction. Matter.js supports all mainstream browsers. Additionally, it is suitable for mobile devices as it detects touches and is responsive. All of these features make it worth your time to learn how to use the engine, as this makes it easy to create a physics-based 2D game or simulation. In this tutorial, I will cover the basics of this library, including its installation and usage, and provide a

Auto Refresh Div Content Using jQuery and AJAXMar 08, 2025 am 12:58 AM

This article demonstrates how to automatically refresh a div's content every 5 seconds using jQuery and AJAX. The example fetches and displays the latest blog posts from an RSS feed, along with the last refresh timestamp. A loading image is optiona

See all articles