[removed] How do I print a message to the error console?

Question

How can I print a message to the error console, preferably including a variable?

For example, something like:

print(\'x=%d\', x);

Answer 1

With es6 syntax you can use:

console.log(`x = ${x}`);

Answer 2

console.log("your message here");

working for me.. i'm searching for this.. i used Firefox. here is my Script.

 $('document').ready(function() {
console.log('all images are loaded');
});

works in Firefox and Chrome.

Answer 3

A note about 'throw()' mentioned above. It seems that it stops execution of the page completely (I checked in IE8) , so it's not very useful for logging "on going processes" (like to track a certain variable...)

My suggestion is perhaps to add a textarea element somewhere in your document and to change (or append to) its value (which would change its text) for logging information whenever needed...

Answer 4

Exceptions are logged into the JavaScript console. You can use that if you want to keep Firebug disabled.

function log(msg) {
    setTimeout(function() {
        throw new Error(msg);
    }, 0);
}

Usage:

log('Hello World');
log('another message');

Answer 5

Install Firebug and then you can use console.log(...) and console.debug(...), etc. (see the documentation for more).

Answer 6

One good way to do this that works cross-browser is outlined in Debugging JavaScript: Throw Away Your Alerts!.