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 n
How about something as simple as:
console.log = function(message) {$('#debugDiv').append('<p>' + message + '</p>');};
console.error = console.debug = console.info = console.log
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.
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")));
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)
.
<!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>
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