Data text html charset utf 8 base64 decode

Base64 в JavaScript и UTF-8

В JavaScript есть две функции для декодирования и кодирования строк base64:

btoa() – кодирует строку в Base64:

var value = window.btoa('Encode a string'); console.log(value);

var value = window.atob('RW5jb2RlIGEgc3RyaW5n'); console.log(value);

Но в большинстве браузеров они не работают с кириллицей в UTF-8 и символами эмодзи.
В консоле браузера будет ошибка:

Uncaught DOMException: Failed to execute ‘btoa’ on ‘Window’: The string to be encoded contains characters outside of the Latin1 range.

Исправить это можно несколькими способами:

Метод 1

Кодирование

function utf8_to_b64(str) < return window.btoa(unescape(encodeURIComponent(str))); >var value = utf8_to_b64('Текст с эмодзи 😀😃😄'); console.log(value);

Декодирование

function b64_to_utf8(str) < return decodeURIComponent(escape(window.atob(str))); >var value = b64_to_utf8('0KLQtdC60YHRgiDRgSDRjdC80L7QtNC30Lgg8J+YgPCfmIPwn5iE'); console.log(value);

Метод 2

Мини-библиотека base64.js (5kb), которая предварительно конвертирует строку в UTF-8.

Кодирование

var value = Base64.encode('Текст с эмодзи 😀😃😄'); console.log(value);

Декодирование

var value = Base64.decode('0KLQtdC60YHRgiDRgSDRjdC80L7QtNC30Lgg8J+YgPCfmIPwn5iE'); console.log(value);

Если кодировка HTML страницы в UTF-8, то метод Base64.decode вернет кракозябры т.к. происходит двойная перекодировка.

Источник

Decode from Base64 format

Meet Base64 Decode and Encode, a simple online tool that does exactly what it says: decodes from Base64 encoding as well as encodes into it quickly and easily. Base64 encode your data without hassles or decode it into a human-readable format.

Base64 encoding schemes are commonly used when there is a need to encode binary data, especially when that data needs to be stored and transferred over media that are designed to deal with text. This encoding helps to ensure that the data remains intact without modification during transport. Base64 is used commonly in a number of applications including email via MIME, as well as storing complex data in XML or JSON.

• Character set: In case of textual data, the encoding scheme does not contain the character set, so you have to specify which character set was used during the encoding process. It is usually UTF-8, but can be many others; if you are not sure then play with the available options or try the auto-detect option. This information is used to convert the decoded data to our website’s character set so that all letters and symbols can be displayed properly. Note that this is irrelevant for files since no web-safe conversions need to be applied to them.
• Decode each line separately: The encoded data usually consists of continuous text, so even newline characters are converted into their Base64-encoded forms. Prior to decoding, all non-encoded whitespaces are stripped from the input to safeguard the input’s integrity. This option is useful if you intend to decode multiple independent data entries that are separated by line breaks.
• Live mode: When you turn on this option the entered data is decoded immediately with your browser’s built-in JavaScript functions, without sending any information to our servers. Currently, this mode supports only the UTF-8 character set.

All communications with our servers come through secure SSL encrypted connections (https). We delete uploaded files from our servers immediately after being processed and the resulting downloadable file is deleted right after the first download attempt or 15 minutes of inactivity (whichever is shorter). We do not keep or inspect the contents of the submitted data or uploaded files in any way. Read our privacy policy below for more details.

Our tool is free to use. From now on, you don’t need to download any software for such simple tasks.

Details of the Base64 encoding

Base64 is a generic term for a number of similar encoding schemes that encode binary data by treating it numerically and translating it into a base-64 representation. The Base64 term originates from a specific MIME-content transfer encoding.

The particular choice of characters to make up the 64 characters required for Base64 varies between implementations. The general rule is to choose a set of 64 characters that is both 1) part of a subset common to most encodings, and 2) also printable. This combination leaves the data unlikely to be modified in transit through systems such as email, which were traditionally not 8-bit clean. For example, MIME’s Base64 implementation uses A-Z, a-z, and 0-9 for the first 62 values, as well as «+» and «/» for the last two. Other variations, usually derived from Base64, share this property but differ in the symbols chosen for the last two values; an example is the URL and filename safe «RFC 4648 / Base64URL» variant, which uses «-» and «_».

Here’s a quote snippet from Thomas Hobbes’s Leviathan:

«Man is distinguished, not only by his reason, but . «

This is represented as an ASCII byte sequence and encoded in MIME’s Base64 scheme as follows:

In the above quote the encoded value of Man is TWFu. Encoded in ASCII, the letters «M», «a», and «n» are stored as the bytes 77, 97, 110, which are equivalent to «01001101», «01100001», and «01101110» in base-2. These three bytes are joined together in a 24 bit buffer producing the binary sequence «010011010110000101101110». Packs of 6 bits (6 bits have a maximum of 64 different binary values) are converted into 4 numbers (24 = 4 * 6 bits) which are then converted to their corresponding values in Base64.

Text content	M								a								n
ASCII	77								97								110
Bit pattern	0	1	0	0	1	1	0	1	0	1	1	0	0	0	0	1	0	1	1	0	1	1	1	0
Index	19						22						5						46
Base64-encoded	T						W						F						u

As this example illustrates, Base64 encoding converts 3 uncoded bytes (in this case, ASCII characters) into 4 encoded ASCII characters. Switch to mobile version

Источник

Hiding HTML Using Data URIs and base64

I’ve been spending the past few evenings noodling with the HTML5 element. I often bring up the HTML Canvas 2D Context Working Draft specification. The spec shows what functions are available to the canvas’ context, and the examples are instructive. However, the spec also introduced me to a method for «hiding» HTML text directly inside another HTML file, using the «data URI» technique.

In the spec, one of the examples shows a very nice graphics hack to display pretty glowing lines.

The spec does show the example «code» that renders this display. However, if you were to look at the HTML of the spec page (or of this page, for example), you’ll see a block of code that looks like this:

«Whoa,» I thought. «Here’s a way to mask HTML!»

Intrigued, I learned that a «data URI» (NOTE: the URI is the string that the «href» attribute is set to) can express any «resource» MimeType. In this case, the MimeType is «text/html;charset=utf8», which means that the data encoded is an HTML page (using the UTF-8 character set). This data URI technique can also be used for embedding small images such as logos. Specifying «base64» says that the resource is encoded in Base64.

Because I knew that the base64 data in the above link was just HTML, I spent a little time trying to find out how to translate it back into HTML. I stumbled on a page that showed me how to do the translation of base64 back to English on the UNIX command line. The page offered some one liners in Perl, but the comments yielded the technique I ended up using: the base64 utility command.

Since I have Cygwin, I already have this base64 utility. I saved the base64 data into a text file (keeping it all on one line), and ran it as follows:

The «-d» switch says to decode the data. I did get hung up with some partially decoded files. After looking at the output of a good encoding, I saw that the base64 data in the «pretty glowing lines» code contained plus signs ( + ). These were hard to see as they were entity encoded (%2B). However, the broken output suggested a break of some sort. I ended up replacing every «%2B» in the file with the + sign.

I did think that this base64 data URI would be a great way to «hide» the HTML (at least from non-technical people). However, while writing this post, I saw that the resulting HTML page from the base64 data is already translated! Just view the source of the «pretty glowing lines» demo page, and what you see is regular human-readable HTML. So much for trying to be secretive with data URIs!

It does lead me to ask why they (the World Wide Web Consortium) would even use this technique to begin with. The only thing I could come up with was that they wanted to keep the example with the specification. That’s a good reason: anytime they send around the HTML of the spec, they send along the examples as well. Convenient!

Источник

Декодер Base64

Ввод текста сначала кодируется как двоичный битовый поток кодов ASCII каждого символа.

Каждые 6 битов битового потока кодируются в разряд base64.

Вывод закодированной текстовой строки base64:

Изображение в пример кодировки base64

Схема URI данных изображения с выводом данных в кодировке base64:

data:image/jpeg;base64, — заголовок схемы URI данных.

/9j/4AAQSkZ. — это закодированные данные base64.

HTML

Фон CSS с URI данных base64

body background-image: url(‘data:image/jpeg;base64,/9j/4AAQSkZ. ‘);
>

Смотрите также

• Кодировщик Base64 ►
• Кодировщик URL
• Декодер URL
• Изображение в base64
• Base64 для изображения
• Конвертер ASCII в двоичный
• Конвертер ASCII в шестнадцатеричный
• Конвертер двоичного кода в ASCII
• Конвертер шестнадцатеричного кода в ASCII
• Преобразование чисел
• Преобразование изображений
• Таблица ASCII
• Символы Unicode
• Проверка заголовка HTTP
• Проверка статуса HTTP

ВЕБ-ИНСТРУМЕНТЫ

• 301 генератор редиректа
• Декодер Base64
• Кодировщик Base64
• Base64 для изображения
• Редактор HTML
• Генератор HTML-ссылок
• Генератор HTML-таблиц
• Проверка заголовка HTTP
• Проверка статуса HTTP
• Изображение в Base64
• Онлайн-линейка пикселей
• Разрешение экрана
• Тестер разрешения экрана
• Просмотрщик / редактор SVG
• Кодировщик URL
• Декодер URL
• Размер окна

БЫСТРЫЕ ТАБЛИЦЫ

Этот веб-сайт использует файлы cookie для улучшения вашего опыта, анализа трафика и отображения рекламы. Учить больше

Источник