uBlock/assets/resources/run-at.js

81 lines
2.5 KiB
JavaScript

/*******************************************************************************
uBlock Origin - a comprehensive, efficient content blocker
Copyright (C) 2019-present Raymond Hill
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see {http://www.gnu.org/licenses/}.
Home: https://github.com/gorhill/uBlock
The scriptlets below are meant to be injected only into a
web page context.
*/
import { safeSelf } from './safe-self.js';
/* eslint no-prototype-builtins: 0 */
/**
* @helperScriptlet run-at.fn
*
* @description
* Execute a function at a specific page-load milestone.
*
* @param fn
* The function to call.
*
* @param when
* An identifier which tells when the function should be executed.
* See <https://developer.mozilla.org/en-US/docs/Web/API/Document/readyState>.
*
* @example
* `runAt(( ) => { start(); }, 'interactive')`
*
* */
export function runAt(fn, when) {
const intFromReadyState = state => {
const targets = {
'loading': 1, 'asap': 1,
'interactive': 2, 'end': 2, '2': 2,
'complete': 3, 'idle': 3, '3': 3,
};
const tokens = Array.isArray(state) ? state : [ state ];
for ( const token of tokens ) {
const prop = `${token}`;
if ( targets.hasOwnProperty(prop) === false ) { continue; }
return targets[prop];
}
return 0;
};
const runAt = intFromReadyState(when);
if ( intFromReadyState(document.readyState) >= runAt ) {
fn(); return;
}
const onStateChange = ( ) => {
if ( intFromReadyState(document.readyState) < runAt ) { return; }
fn();
safe.removeEventListener.apply(document, args);
};
const safe = safeSelf();
const args = [ 'readystatechange', onStateChange, { capture: true } ];
safe.addEventListener.apply(document, args);
}
runAt.details = {
name: 'run-at.fn',
dependencies: [
safeSelf,
],
};