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Text Translate API


Extension developers would like to be able to translate the text of pages. Transforming arbitrary DOM trees into blocks of text of suitable length for translation is hard, and potentially time consuming if done naively. Noticing dynamic updates to the page is also difficult to do correctly. Also, modifying the content of text nodes may confuse some web applications who weren't expecting mutation events to occur (this is probably a minor problem though).


Expose an API that can feed an extension process blocks of text to translate. Chromium takes care of the hard work of creating nice blocks of text, removing html tags, noticing dynamic updates, handling races between the extension and renderer process, and modifying the text of the page in the most compat-friendly way.

The extension just has to translate and return the text when requested.



// Start translating text for the specified tab. The callback gets called

// repeatedly until stop() is called. Each time it is called it will pass

// a block of text that needs translating.

// NOTE: tab.documentId doesn't yet exist and needs to be added.

void start(int tabId, int documentId, void callback(int blockId, string text))

// The extension should call this function when a block of text has been

// translated.

void updateBlock(int blockId, string translatedText))

// Stop translating text for a tab.

void stop(int tabId, int documentId)

Example Usage

// Start translating

chrome.tabs.getCurrent(null, function(tab) {

chrome.textTranslate.start(, tab.documentId, translate);


function translate(blockId, text) {

var req = new XMLHttpRequest();"POST", "", false);

req.onreadystatechange = function() {

if (req.readyState == 4) {

chrome.textTranslate.updateBlock(blockId, req.responseText);





Implementation Details

TODO: Flesh this area out Here are some ideas: