Note that btoa() expects to be passed binary data, and will throw an exception if the given string contains any characters whose UTF-16 representation occupies more than one byte. The whole point of base64 is to provide a safe way of converting arbitrary binary data into a text format which can be reliably embedded in other text. Every character in the output is printable ASCII text. If only one or two bytes are encoded, then the sign is used as the fill character at the end. Base64 encoding is applied to binary data (a sequence of bytes, or octets if you want to be even more picky), and the result is text.

Any base64 encoded content is therefore a valid. In base64, every 3 bytes of data are encoded as 4 characters. The algorithm used by atob() and btoa() is specified in RFC 4648, section 4. The base64 encoding of arbitrary byte sequences uses only characters from the ASCII (Basic Latin) inventory.

atob(): decodes a Base64-encoded string('atob' should be read as 'ASCII to binary').

btoa(): creates a Base64-encoded ASCII string from a 'string' of binary data ('btoa' should be read as 'binary to ASCII').

In JavaScript there are two functions respectively for decoding and encoding Base64 strings: One common application of Base64 encoding on the web is to encode binary data so it can be included in a data: URL. Base64 is commonly used in a number of applications including email via MIME, and storing complex data in XML. This is to ensure that the data remain intact without modification during transport. The term Base64 originates from a specific MIME content transfer encoding.īase64 encoding schemes are commonly used when there is a need to encode binary data that needs to be stored and transferred over media that are designed to deal with ASCII. The result after decoding is as follows.Base64 is a group of similar binary-to-text encoding schemes that represent binary data in an ASCII string format by translating it into a radix-64 representation. of the email contains non-ASCII characters.

The coding Base64 it is often used when there is a need to transfer and store binary data to a device designed to work with textual data. This format is used when the subject, recipient, etc. Base64 encoding is case sensitive, so when trying to decode be aware that alphabet variations can alter your entire output. SGVsbG8= Email MIME message header type (RFC 2047)ĭenCode also supports decoding of MIME message header format (RFC 2047), such as below. Connect all the characters to get the Base64 conversion result. URL and filename Encoding Here encode the. If outside any character contain other than base64, then the decoder rejects it. Although, It was later extended to support non US-ASCII text messages as well as non-text messages such as audio and images, It is still recommended to encode the data to ASCII charset for backward. Simple Encoding Here, encode the data by mapping to the character set in A-Za-z0-9+/ and does not add any line separator character in the output. The common concept is to select a set of 64. One example of such a system is Email (SMTP), which was traditionally designed to work with plain text data in the 7-bit US-ASCII character set. Convert every 4 characters, and if it is less than 4 characters, pad the end with '='. The specific set of characters chosen for the 64 characters needed for the base can vary among implementations. Convert to characters using a conversion table. The most common encoding is the base64 encoding defined in RFC. This class provides the methods to use to perform the encode and. 010010 000110 010101 101100 011011 000110 111100ģ. An Encoding is a radix 64 encoding/decoding scheme, defined by a 64-character alphabet. The Base 64 technique is to map the binary data to the A-za-z0-9+/ set of characters. If it is less than 6 bits, pad it with '0' at the end. This module provides functions for encoding binary data to printable ASCII characters and decoding such encodings back to binary data. For example, if you convert 'Hello' with Base64, it will be as follows.ġ.

Character set for base64 encoding