XHR's onreadystatechange execution order

[woshiwanglizhi]

lottie-web/player/js/utils/asset_loader.js

Lines 15 to 46 in 1067722

	function loadAsset(path, callback, errorCallback) {
	var response;
	var xhr = new XMLHttpRequest();
	xhr.open('GET', path, true);
	// set responseType after calling open or IE will break.
	try {
	// This crashes on Android WebView prior to KitKat
	xhr.responseType = 'json';
	} catch (err) {} // eslint-disable-line no-empty
	xhr.send();
	xhr.onreadystatechange = function () {
	if (xhr.readyState === 4) {
	if (xhr.status === 200) {
	response = formatResponse(xhr);
	callback(response);
	} else {
	try {
	response = formatResponse(xhr);
	callback(response);
	} catch (err) {
	if (errorCallback) {
	errorCallback(err);
	}
	}
	}
	}
	};
	}
	return {
	load: loadAsset,
	};
	}());

We need to change the order of execution here,Place the onreadystatechange event before the open and send assignments.
Since onreadystatechange is intercepted in open in some third-party plug-ins (such as Sentry), subsequent assignments to onreadystatechange break this mechanism, causing an exception.

https://github.com/getsentry/sentry-javascript/blob/d7798ebb4877f41faa6d1a67ce682b5b4043dde2/packages/tracing/src/browser/request.ts#L214-L270