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Add: a naive browser polyfill

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eight04 2020-07-10 19:00:33 +08:00 committed by tophf
parent c37bd92e78
commit 2d4b885a71
1 changed files with 21 additions and 5 deletions
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26
js/polyfill.js
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@ -15,16 +15,13 @@ self.INJECTED !== 1 && (() => {
if (!self.chrome) return; if (!self.chrome) return;
// the rest is for content scripts and our extension pages // the rest is for content scripts and our extension pages
self.browser = polyfillBrowser();
/* Promisifies the specified `chrome` methods into `browser`. /* Promisifies the specified `chrome` methods into `browser`.
The definitions is an object like this: { The definitions is an object like this: {
'storage.sync': ['get', 'set'], // if deeper than one level, combine the path via `.` 'storage.sync': ['get', 'set'], // if deeper than one level, combine the path via `.`
windows: ['create', 'update'], // items and sub-objects will only be created if present in `chrome` windows: ['create', 'update'], // items and sub-objects will only be created if present in `chrome`
} */ } */
self.promisifyChrome = definitions => { self.promisifyChrome = definitions => {
// a web page may have <html id="browser"> which creates a global variable `browser` pointing to this element
if (!self.browser || !self.browser.runtime && !self.browser.promisifyChrome) {
self.browser = Object.defineProperty({}, 'promisifyChrome', {value: true});
}
for (const [scopeName, methods] of Object.entries(definitions)) { for (const [scopeName, methods] of Object.entries(definitions)) {
const path = scopeName.split('.'); const path = scopeName.split('.');
const src = path.reduce((obj, p) => obj && obj[p], chrome); const src = path.reduce((obj, p) => obj && obj[p], chrome);
@ -32,13 +29,14 @@ self.INJECTED !== 1 && (() => {
const dst = path.reduce((obj, p) => obj[p] || (obj[p] = {}), browser); const dst = path.reduce((obj, p) => obj[p] || (obj[p] = {}), browser);
for (const name of methods) { for (const name of methods) {
const fn = src[name]; const fn = src[name];
if (!fn || dst[name]) continue; if (!fn || dst[name].isPromisified) continue;
dst[name] = (...args) => new Promise((resolve, reject) => dst[name] = (...args) => new Promise((resolve, reject) =>
fn.call(src, ...args, (...results) => fn.call(src, ...args, (...results) =>
chrome.runtime.lastError ? chrome.runtime.lastError ?
reject(chrome.runtime.lastError) : reject(chrome.runtime.lastError) :
resolve(results.length <= 1 ? results[0] : results))); resolve(results.length <= 1 ? results[0] : results)));
// a couple of callbacks have 2 parameters (we don't use those methods, but just in case) // a couple of callbacks have 2 parameters (we don't use those methods, but just in case)
dst[name].isPromisified = true;
} }
} }
}; };
@ -107,4 +105,22 @@ self.INJECTED !== 1 && (() => {
} catch (err) { } catch (err) {
Object.defineProperty(self, 'sessionStorage', {value: {}}); Object.defineProperty(self, 'sessionStorage', {value: {}});
} }
function polyfillBrowser() {
return createTrap(chrome, null);
function createTrap(base, parent) {
return new Proxy(typeof base === 'function' ? () => {} : {}, {
get: (target, prop) => {
if (target[prop]) return target[prop];
if (base[prop] && (typeof base[prop] === 'object' || typeof base[prop] === 'function')) {
target[prop] = createTrap(base[prop], base);
return target[prop];
}
return base[prop];
},
apply: (target, thisArg, args) => base.apply(parent, args)
});
}
}
})(); })();