How to read from Chrome's console in JavaScript
JavascriptGoogle ChromeJavascript Problem Overview
I would like to put a button in my app, if you press it it will get the contents of everything that was written to the console and email it to me (for reporting bugs). I know I can keep a variable around and every time I do a console.log also append the message to that variable but I am trying to keep the memory consumption of the app low so it would be much more efficient just to grab it from the console.
Is there a way to retrieve the console messages from javascript?
Javascript Solutions
Solution 1 - Javascript
You can't. What's in the console can't be read from JavaScript.
What you can do is hook the console.log function so that you store when it logs :
console.stdlog = console.log.bind(console);
console.logs = [];
console.log = function(){
console.logs.push(Array.from(arguments));
console.stdlog.apply(console, arguments);
}
console.logs contains all what was logged. You can clean it at any time by doing console.logs.length = 0;.
You can still do a standard, non storing, log by calling console.stdlog.
Solution 2 - Javascript
get all console data
> how to read browser console error in js?
https://stackoverflow.com/questions/19846078/how-to-read-from-chromes-console-in-javascript
https://www.quora.com/How-do-I-read-console-window-errors-from-Chrome-using-JavaScript
logs
console.defaultLog = console.log.bind(console);
console.logs = [];
console.log = function(){
// default & console.log()
console.defaultLog.apply(console, arguments);
// new & array data
console.logs.push(Array.from(arguments));
}
error
console.defaultError = console.error.bind(console);
console.errors = [];
console.error = function(){
// default & console.error()
console.defaultError.apply(console, arguments);
// new & array data
console.errors.push(Array.from(arguments));
}
warn
console.defaultWarn = console.warn.bind(console);
console.warns = [];
console.warn = function(){
// default & console.warn()
console.defaultWarn.apply(console, arguments);
// new & array data
console.warns.push(Array.from(arguments));
}
debug
console.defaultDebug = console.debug.bind(console);
console.debugs = [];
console.debug = function(){
// default & console.debug()
console.defaultDebug.apply(console, arguments);
// new & array data
console.debugs.push(Array.from(arguments));
}
Solution 3 - Javascript
I have used this code in the past to capture all console activity and store it with types and timestamps in console.everything for sending back to the server for diagnosing form data entry issues. I run this code as early as possible in the <head> element.
if (console.everything === undefined)
{
console.everything = [];
console.defaultLog = console.log.bind(console);
console.log = function(){
console.everything.push({"type":"log", "datetime":Date().toLocaleString(), "value":Array.from(arguments)});
console.defaultLog.apply(console, arguments);
}
console.defaultError = console.error.bind(console);
console.error = function(){
console.everything.push({"type":"error", "datetime":Date().toLocaleString(), "value":Array.from(arguments)});
console.defaultError.apply(console, arguments);
}
console.defaultWarn = console.warn.bind(console);
console.warn = function(){
console.everything.push({"type":"warn", "datetime":Date().toLocaleString(), "value":Array.from(arguments)});
console.defaultWarn.apply(console, arguments);
}
console.defaultDebug = console.debug.bind(console);
console.debug = function(){
console.everything.push({"type":"debug", "datetime":Date().toLocaleString(), "value":Array.from(arguments)});
console.defaultDebug.apply(console, arguments);
}
}
Solution 4 - Javascript
QA Collective's solution is very nice but has a lot of repeated code and doesn't capture errors that are not printed via the console.log, console.error, etc.
Here's the DRY and extended version of his solution that captures more error messages that show up in the console:
if (console.everything === undefined) {
console.everything = [];
function TS(){
return (new Date).toLocaleString("sv", { timeZone: 'UTC' }) + "Z"
}
window.onerror = function (error, url, line) {
console.everything.push({
type: "exception",
timeStamp: TS(),
value: { error, url, line }
})
return false;
}
window.onunhandledrejection = function (e) {
console.everything.push({
type: "promiseRejection",
timeStamp: TS(),
value: e.reason
})
}
function hookLogType(logType) {
const original= console[logType].bind(console)
return function(){
console.everything.push({
type: logType,
timeStamp: TS(),
value: Array.from(arguments)
})
original.apply(console, arguments)
}
}
['log', 'error', 'warn', 'debug'].forEach(logType=>{
console[logType] = hookLogType(logType)
})
}
I also changed the timestamp format to use the ISO format in UTC timezone, to be able to compare time stamps in different time zones more easily.
Solution 5 - Javascript
If you're working on vue.js, you can actually do this:
data () {
return {
data: []
}
},
created () {
let current_log = console.log;
console.log = msg => {
if (msg !== undefined) this.data.push(msg);
current_log.apply(null, arguments);
}
}
All logs from console will be captured and stored in data
Solution 6 - Javascript
If you just want to catch windows errors (Browser's developer tool), you just need to use the window.onerror listener. and the most important thing is to keep returning it false because If you return true in your callback, then the propagation of the error will stop and won't be log in the console anymore .
window.onerror = function myErrorHandler(err, url, line) {
//Do some stuff
console.log(err) // Uncaught SyntaxError: Invalid or unexpected token at Line no:- 1
return false; // so you still log errors into console
}