Convert file to base64 javascript

With the development of Internet technology and the increase in application scenarios, file transfers have become more and more frequent. However, during the transmission process, the protocol we use only supports the transmission of text information. If you want to transmit a file, the file content needs to be converted into text information. Among them, a popular conversion method is to convert the file into a base64 string.

What is base64?

In the computer field, base64 is an encoding method. It converts binary data into a text string consisting of a set of 64 characters. These characters include 26 uppercase letters, 26 lowercase letters, 10 numbers and 2 special characters " " and "/". Because base64-encoded strings contain only these characters, they can be safely transferred to multiple systems without being affected by system differences.

Why should we convert the file to base64 string?

In the computer field, files can be stored or transmitted in the form of binary data. However, if you want to transfer the file to another system or website, there may be problems with the file format due to system differences. Therefore, it is necessary to convert the file content into a base64 string, so as to avoid file format problems and ensure the transmission and sharing of files between different systems.

How to convert a file to base64 string?

In Javascript, we can read the file content as binary data through the FileReader object. Then, use the btoa() function to encode the binary data into a base64 string. The following is an example of Javascript code that converts a file to a base64 string:

function convertFileToBase64(file) {
  const reader = new FileReader();
  reader.readAsBinaryString(file);
  reader.onload = function () {
    const base64String = btoa(reader.result);
    console.log(base64String); // 输出base64字符串
  }
}

In this example, we have created a function called convertFileToBase64(). It takes a file parameter and reads the file contents as binary data through a FileReader object. Then, after the reading is complete, use the btoa() function to encode the binary data into a base64 string and print it to the console.

It should be noted that you may encounter some problems when using the FileReader object to read files. For example, if the file read is too large, it may cause the browser to crash. Therefore, we need to handle file reading operations carefully and ensure the stability of the code.

Conclusion

Converting files to base64 strings is a common operation that ensures there are no issues with the format when transferring and sharing files between different systems. In Javascript, we can use the FileReader object and the btoa() function to convert files into base64 strings. However, we need to be careful when performing file reading operations to ensure the stability and reliability of the code.

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