How to write txt file in javascript

As a front-end development language, JavaScript is widely used in web development. Among them, file reading and writing operations are an inevitable part of development, because in many scenarios it is necessary to write some data to local files to facilitate subsequent processing and use. This article will introduce how to use JavaScript to write txt files.

1. Create a txt file

To write a file, we first need to create a txt file. This can be achieved through the following code:

var content = "这是要写进txt文件的内容";
var blob = new Blob([content], {type: "text/plain;charset=utf-8"});
saveAs(blob, "newfile.txt");

The above code first defines a string type variable content to save the content to be written to the file. Next, we convert it into a Blob instance through the Blob object, defining the type as "text/plain;charset=utf-8", indicating that the content is text type and the encoding format is "UTF-8". Finally, save the created Blob instance with the file name "newfile.txt" through the saveAs() function.

2. Write data to the txt file

After we have the txt file, we can use JavaScript to write data to the file. In order to achieve this purpose, we need to use the FileWriter object. There is a write() function in the FileWriter object, which can be used to write data to the specified file.

The following is a simple example showing how to write data to an already created txt file.

var file = new File(["这是初始内容"], "newfile.txt", {type: "text/plain;charset=utf-8"});
var writer = new FileWriter();

writer.write("这是写入的内容");
writer.save(file);

The above code first defines a File object named file, the type is "text/plain", the encoding method is "UTF-8", the file name is "newfile.txt", and contains the initial content" This is the initial content." Next, we define a FileWriter object named writer and write new content to the file through the write() function "This is the written content". Finally, we use the save() function to store the content into the file just defined.

3. Expansion: Use the File API to create a txt file

In the previous example, we used the Blob instance and File object to create a txt file. However, if you don't want to create the txt file manually, you can also use some File API to create it.

function createFile() {
    var file = new File([""], "newfile.txt", {type: "text/plain;charset=utf-8"});
    return file;
}

In the above code, we define a createFile() function, which will return a file named "newfile.txt", type "text/plain", and encoding method "UTF-8" Blank document. We just need to fill in the data we want to store in the file.

4. Summary

This article introduces how to use JavaScript to realize the reading and writing operations of txt files, including creating txt files, writing data to txt files, etc. At the same time, we also learned the commonly used objects and functions in the File API. I hope this article can inspire you to learn JavaScript file operations.

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