javascript base64 garbled code

Recently, many websites have encountered garbled code problems when using Javascript to Base64 encode images and text. This situation is usually caused by errors in the encoding method or encoding process. In order to solve these problems, we need to have a deep understanding of Base64 encoding in Javascript and how to use it correctly.

What is Base64?

Base64 is a method of encoding binary data into ASCII characters. It converts 3 8-bit bytes into 4 6-bit bytes and pads the result into an ASCII string using one of the 64 characters of the specified character set. During data transmission, Base64 is usually used to convert binary data into ASCII characters so that it will not be processed incorrectly during transmission. It is frequently used for email and data transfer.

Using the implementation of Base64 in Javascript

There is already an implementation of Base64 in Javascript, so there is no need to write the algorithm yourself. We can use the window.btoa() method to Base64 encode the string and the window.atob() method to reverse decode it. These methods only work with ASCII characters and are not supported in browsers below IE9.

For example:

var str = "Hello World";
var encodedString = window.btoa(str); // 编码
var decodedString = window.atob(encodedString); // 解码
console.log(encodedString); // SGVsbG8gV29ybGQ=
console.log(decodedString); // Hello World

When encoding pictures or other binary data, we need to pass them as binary data views to the window.btoa() method, for example:

var byteArray = new Uint8Array([73, 69, 78, 68, 255, 216, 255]);
var encodedString = window.btoa(String.fromCharCode.apply(null, byteArray)); // 编码
console.log(encodedString); // SU5ET1+J/g==

String.fromCharCode.apply(null, byteArray) is used here to convert the binary data view into an ordinary string and then encode it.

How to solve the problem of Base64 encoding garbled characters

Base64 encoding garbled characters are usually caused by the following reasons:

1. For non-ASCII characters, the window.btoa() method will resulting in encoding errors. Additionally, certain characters such as , /, = characters may cause encoding errors.
2. In some cases, the browser may automatically add and
   newline characters after Base64 encoding, which will cause encoding errors.
3. When encoding binary data, you need to use the correct method to convert it to a string.

The method to solve these problems is as follows:

1. To solve the encoding error for non-ASCII characters: you can use third-party libraries, such as js-base64 or CryptoJS, which support UTF -8 encoded binary data. For example:

var str = "你好世界";
var encodedString = window.btoa(unescape(encodeURIComponent(str))); // 使用第三方库
console.log(encodedString); //5L2g5aW977yM5LiW55WM

Here, unescape(encodeURIComponent(str)) is used to convert the UTF-8 encoded string to an ASCII string, and then window.btoa() is used to encode it.

2. Avoid automatic addition and
   newlines: When encoding pictures or binary data, you can use an array buffer or Blob object to pass the binary data, for example:

var byteArray = new Uint8Array([73, 69, 78, 68, 255, 216, 255]);
var blob = new Blob([byteArray], {type: 'image/jpeg'});
var reader = new FileReader();
reader.onloadend = function() {
  console.log(reader.result);
};
reader.readAsDataURL(blob); // 编码，避免自动添加和
换行符

Here, use a Blob object to pass binary data and a FileReader object to convert it to a Data URL. Data URLs do not contain and
newline characters.

3. Correctly encode binary data: When converting an array of binary data to a string, you should use the correct encoding method, usually using the TextDecoder API or TextEncoder API. For example:

var byteArray = new Uint8Array([73, 69, 78, 68, 255, 216, 255]);
var decoder = new TextDecoder('utf-8');
var str = decoder.decode(byteArray); // 将二进制数据数组转换为字符串
var encodedString = window.btoa(str); // 编码
console.log(encodedString);

Here, we use TextDecoder API to convert the binary data array into UTF-8 encoded string and then encode it using window.btoa() method.

Conclusion

In Javascript, using Base64 for encoding and decoding is an effective way, but in actual applications, you need to pay attention to its implementation details and precautions to avoid encoding errors and Garbled characters. Using correct encoding methods and third-party libraries for encoding and decoding, as well as using array buffers or Blob objects when encoding binary data can help us solve the Base64 garbled problem.

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