Showing console errors and alerts in a div inside the page

I'm building a debugging tool for my web app and I need to show console errors in a div. I know I can use my own made console like object and use it, but for future use I need to send all console errors to window. Actually I want to catch console events.

Answers:

Answer

To keep the console working:

if (typeof console  != "undefined") 
    if (typeof console.log != 'undefined')
        console.olog = console.log;
    else
        console.olog = function() {};

console.log = function(message) {
    console.olog(message);
    $('#debugDiv').append('<p>' + message + '</p>');
};
console.error = console.debug = console.info =  console.log
Answer

Here's a way using closure, containing the old console log function in the scope of the new one.

console.log = (function (old_function, div_log) { 
    return function (text) {
        old_function(text);
        div_log.value += text;
    };
} (console.log.bind(console), document.getElementById("error-log")));
Answer

Else, if you were concerned at keeping log, warn and error separate from one another, you could do something like this (adapted from MST's answer):

var log = document.querySelector('#log');

['log','warn','error'].forEach(function (verb) {
    console[verb] = (function (method, verb, log) {
        return function (text) {
            method(text);
            // handle distinguishing between methods any way you'd like
            var msg = document.createElement('code');
            msg.classList.add(verb);
            msg.textContent = verb + ': ' + text;
            log.appendChild(msg);
        };
    })(console[verb].bind(console), verb, log);
});

where #log is your HTML element. The variable verb is one of 'log', 'warn', or 'error'. You can then use CSS to style the text in a distinguishable way. Note that a lot of this code isn't compatible with old versions of IE.

Answer

How about something as simple as:

console.log = function(message) {$('#debugDiv').append('<p>' + message + '</p>');};
console.error = console.debug = console.info =  console.log
Answer

None of the answers here consider console messages that get passed multiple parameters. E.g. console.log("Error:", "error details")).

The function that replaces the default log function better regards all function arguments (e.g. by using the arguments object). Here is an example:

console.log = function() {
  log.textContent += Array.prototype.slice.call(arguments).join(' ');
}

(The Array.prototype.slice.call(...) simply converts the arguments object to an array, so it can be concatenated easily with join().)

When the original log should be kept working as well:

console.log = (function (old_log, log) { 
    return function () {
        log.textContent += Array.prototype.slice.call(arguments).join(' ');
        old_log.apply(console, arguments);
    };
} (console.log.bind(console), document.querySelector('#log')));

A complete solution:

var log = document.querySelector('#log');
['log','debug','info','warn','error'].forEach(function (verb) {
    console[verb] = (function (method, verb, log) {
        return function () {
            method.apply(console, arguments);
            var msg = document.createElement('div');
            msg.classList.add(verb);
            msg.textContent = verb + ': ' + Array.prototype.slice.call(arguments).join(' ');
            log.appendChild(msg);
        };
    })(console[verb], verb, log);
});

(An example of a framework that emits messages with multiple parameters is Video.js. But there is certainly many others.)

Edit: Another use of multiple parameters is the formatting capabilities of the console (e.g. console.log("Status code: %d", code).

Answer
<!DOCTYPE html>
<html>
<head>
    <title>Page Title</title>
</head>
<body>
    <div id="logger" class="web_console"></div>

    <script type="text/javascript">

        // Overriding console object
        var console = {};

        // Getting div to insert logs
        var logger = document.getElementById("logger");

        // Adding log method from our console object
        console.log = function(text)
        {
            var element = document.createElement("div");
            var txt = document.createTextNode(text);

            element.appendChild(txt);
            logger.appendChild(element);
        }

        // testing
        console.log("Hello World...");
        console.log("WOW");

        /**
            console.log prints the message in the page instead browser console, useful to programming and debugging JS using a Android phone

        */
    </script>
</body>
</html>
Answer

I created a zero-dependency npm module for this case: console-events (surely if you're okay to use nodejs :P)

You can add event listener like that:

const { console } = require('console-events');

console.addEventListener('log', (e) => {
   e.preventDefault(); //if you need to prevent normal behaviour e.g. output to devtools console
   $('#debugDiv').append('<p>' + message + '</p>');
})

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