Question

145

Chrome truncates error messages and adds < omitted> in window.onerror

rated 0 times [ 149] [ 4] / answers: 1 / hits: 5826 / 10 Years ago, wed, march 5, 2014, 12:00:00

We use window.onerror to catch unhandled exceptions (to log them for the dev team, and display a friendly user alert). Recently we noticed that in Google Chrome, the error message got truncated if it was above a certain length, and the text ...<omitted>... was mysteriously added to the error message.

The code below will demonstrate this (in Chrome ver 33.0.1750). I was wondering if anyone else has had this problem?

<html>

    <head>

        <script type=text/javascript>



        window.onerror = function (errorMsg, url, lineNumber) {

            alert('Error: ' + errorMsg);

        }



        var throwError = function () {

            throw new Error(

            'Something went wrong. Something went wrong. Something went wrong. Something went wrong. ' +

            'Something went wrong. Something went wrong. Something went wrong. Something went wrong. ' + 

            'Something went wrong. Something went wrong. Something went wrong. Something went wrong. ' + 

            'Some text gets truncated before this point!');

        }



        </script>

    </head>

    <body>

        <h1>Hello World</h1>

        <input type=button onclick=throwError() value=Throw uncaught error! /><br /><br />

    </body>

</html>

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georginat

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4 Years ago

answered 10 Years ago ammonderekm · Accepted Answer

I found a solution that works well.

Chrome implements the new HTML standard, in which 2 new parameters have been added to the onerror handler, namely: the colNumber, and the error object (including stack trace).

See:

https://mikewest.org/2013/08/debugging-runtime-errors-with-window-onerror

HTML Living Standard

The full error message can be accessed through error.message as per my code sample below. This is a duplicate of the 1st parameter message, it seems like Chrome has decided to truncate message. Not sure why they had to break something that was working... :-(

IE and FireFox (as of my current versions: 11.0.9600 & 26.0) are not yet implementing the new 5-parameter standard, so the code makes allowance for that.

Hope this helps someone!

Code sample to return full error message:

<html>

<head>

    <script type=text/javascript>



    //Chrome passes the error object (5th param) which we must use since it now truncates the Msg (1st param).

    window.onerror = function (errorMsg, url, lineNumber, columnNumber, errorObject) {

        var errMsg;

        //check the errorObject as IE and FF don't pass it through (yet)

        if (errorObject && errorObject !== undefined) {

                errMsg = errorObject.message;

            }

            else {

                errMsg = errorMsg;

            }

        alert('Error: ' + errMsg);

    }



    var throwError = function () {

        throw new Error(

        'Something went wrong. Something went wrong. Something went wrong. Something went wrong. ' +

        'Something went wrong. Something went wrong. Something went wrong. Something went wrong. ' + 

        'Something went wrong. Something went wrong. Something went wrong. Something went wrong. ' + 

        'Text does not get truncated! :-)');

    }



    </script>

</head>

<body>

    <h1>Hello World</h1>

    <input type=button onclick=throwError() value=Throw uncaught error! /><br /><br />

</body>