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Created December 15, 2019 15:56
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Log JS errors as a POST to your server
// <log errors to server>
window.onerror = function (messageOrEvent, source, lineno, colno, error) {
try {
//error message(string).Available as event (sic!) in HTML onerror = "" handler.
messageOrEvent: messageOrEvent,
//URL of the script where the error was raised(string)
source: source,
//Line number where error was raised(number)
lineno: lineno,
//Column number for the line where the error occurred(number)
colno: colno,
//Error Object(object)
error: error
//placeholder array for request parameters
var params = [],
//saves a unique id to prevent creating a new script tags for each error
___guid = window.onerror___guid || (window.onerror___guid = (new Date().getTime() + '-' + new Date().getTime())), //a guidto for the error script element id
//create a new function if none exists with the unique id
___logError = function (___url) {
___domScript = document.getElementById(___guid);
if (!___domScript) {
var ___head = document.head || document.getElementsByTagName('head')[0],
___domScript = document.createElement('script'); = ___guid;
___domScript.dataType = 'json';
___domScript.async = 'async';
___head.insertBefore(___domScript, ___head.firstChild);
___domScript.src = ___url;
params.push('browser=' + encodeURIComponent(((navigator.userAgent + '|' + navigator.vendor + '|' + navigator.platform + '|' + navigator.platform) || '').toString()));
params.push('lineNumber=' + encodeURIComponent((lineno || '').toString()));
params.push('colNumber=' + encodeURIComponent((colno || '').toString()));
params.push('source=' + encodeURIComponent((source || '').toString()));
params.push('error=' + encodeURIComponent((error || '').toString()));
params.push('messageOrEvent=' + encodeURIComponent((messageOrEvent || '').toString()));
params.push('url=' + encodeURIComponent((window.location.href || '').toString()));
// `/JavascriptError` is your servers endpoint
___logError('/url_on_your_server.php?action=report_js_error&' + params.join('&'));
catch (e) {
// squelch, because we don’t want to prevent method from returning true
//When the function returns true, this prevents the firing of the default event handler.
return false;
// </log errors to server>
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