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@freaktechnik freaktechnik/l10n.js
Last active Dec 12, 2017

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Drop-in script to localize HTML sites in WebExtensions like it was the Add-on SDK.
/**
* Translates a HTMl page in the web l10n style from the Add-on SDK with
* WebExtensions strings.
* Large parts of the logic are very similar to the SDK implmentation.
* All you have to do to use this in a document is load it.
*
* It supports some additional attributes:
* - The "translate" attribute is fully respected (see
* https://developer.mozilla.org/en-US/docs/Web/HTML/Global_attributes/translate)
* - "data-l10n-nocontent" means that the text content of the element
* will not be attempted to be translated.
*
* @author Martin Giger
* @license MPL-2.0
*/
function translateElementAttributes(element) {
const attrList = [ 'title', 'accesskey', 'alt', 'label', 'placeholder', 'abbr', 'content', 'download', 'srcdoc', 'value' ];
const ariaAttrMap = {
'aria-label': 'ariaLabel',
'aria-value-text': 'ariaValueText',
'aria-moz-hint': 'ariaMozHint'
};
const attrSeparator = '.';
const presentAttributes = element.dataset.l10nAttrs.split(",");
// Translate allowed attributes.
for(let attribute of presentAttributes) {
let data;
if(attrList.includes(attribute)) {
data = browser.i18n.getMessage(element.dataset.l10nId + attrSeparator + attribute);
}
// Translate ARIA attributes
else if(attribute in ariaAttrMap) {
data = browser.i18n.getMessage(element.dataset.l10nId + attrSeparator + ariaAttrMap[attribute]);
}
if(data && data != "??") {
element.setAttribute(attribute, data);
}
}
}
const C_TRANSLATE_VALUES = [
'yes',
'no'
];
function getTranslateState(element) {
if(element.hasAttribute("translate") && C_TRANSLATE_VALUES.includes(element.getAttribute("translate"))) {
return element.getAttribute("translate");
}
const closestTranslate = element.closest('[translate]:not([translate="inherit"])');
if(closestTranslate) {
return closestTranslate.getAttribute("translate");
}
return "yes";
}
function translateElement(element = document) {
// Set the language attribute of the document.
if(element === document) {
document.documentElement.setAttribute("lang", browser.i18n.getUILanguage().replace("_", "-"));
}
// Get all children that are marked as being translateable.
const children = element.querySelectorAll('*[data-l10n-id]:not([translate="no"])');
for(const child of children) {
if(getTranslateState(child) !== "no") {
if(!child.dataset.l10nNocontent) {
const data = browser.i18n.getMessage(child.dataset.l10nId);
if(data && data != "??") {
child.textContent = data;
}
}
if(child.dataset.l10nAttrs) {
translateElementAttributes(child);
}
}
}
}
document.addEventListener("DOMContentLoaded", () => translateElement(), {
capture: false,
passive: true,
once: true
});
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