whenPageReady.js

// SNIPPET whenPageReady v1.3
// state: [interactive | complete]
// usage: whenPageReady(doStuff, 'interactive');
var whenPageReady = (handler, state = 'complete') => {
	var eventName;

	if (state === 'DOMContentLoaded') { state = 'interactive'; }
	if (state === 'load') { state = 'complete'; }
	if (state !== 'interactive' && state !== 'complete') {
		console.warn('SCRIPTNAME: whenPageReady(): wrong STATE argument: ' + state + '. Defaulting to: "complete".');
		state = 'complete';
	}
	if (state === 'interactive') { eventName = 'DOMContentLoaded'; }
	if (state === 'complete') { eventName = 'load'; }

	if (document.readyState !== 'complete' && (state === 'complete' || document.readyState !== 'interactive')) {
		window.addEventListener(eventName, () => whenPageReady(handler, state));
// 		if (DEBUG) { console.log("SCRIPTNAME: whenPageReady(): page not ready. (readyState = '" + document.readyState + ', desired: ' + state); }
		return;
	}
// 	if (DEBUG) { console.log("SCRIPTNAME: whenPageReady(): page ready (readyState = '" + state + "')"); }
	handler();
};