This may be an easier example while keeping the scope within the namespace:

var test = {
t: function(){
console.log(‘–’);
return this;
},
log: function(m){
console.log(m);
return this;
}
};

test.t().log(‘without a library’).t();


function test(){
console.log(’—’);
return this;
}

test().log(’Hey, I am doing this with jQuery!’).test();


if the code is running at global scope, “this” is the global object, i.e. the window. So there’s no reason to do any chaining in the first place. A bare function call is the same as calling a window method, so the code is equivalent to:


function test(){
console.log(’—’);
}

test();
log(’Hey, I am doing this with jQuery!’);
test();


But your point is well taken that you could add a .log method to any object. For example, here is a log method for strings:


String.prototype.log = function( format ) {
window.console && console.log(
format || 'String length %i, value "%s"',
this.length, this );
return ''+this;
};

'just testing'.log().slice(5,9).log();


If you paste that into the Firebug console (in multiline mode) you will see:


String length 12, value "just testing"
String length 4, value "test"
"test"


Note the use of “return ”+this;” instead of just “return this;” – that causes the function to return a primitive string instead of a string object, which gives less surprising results at least in this test case. (Try changing it to “return this;” and see what Firebug displays.)

http://pastemonkey.org/paste/471a49a0-fc54-4ca8-b8e7-5411404fdb0d

JFR
http://www.debugbar.com

The great thing is that it helps a lot to avoid chaining-breakups for logging purposes. Eg. something like this would be much simpler:

var toLog = $(“.selectotor”);
console.log(toLog);
toLog.doSomething();

Just doing $(“.selector).log().doSomething() is that much simpler. And you can add the check if the console object exists to the log plugin implementation.

function test(){
console.log(‘—’);
return this;
}

function log(msg){
console.log(msg);
return this;
}

test().log(‘Hey, I am doing this with jQuery!’).test();

Short, sweet, and very useful.

And dare I admit that all the time I’ve been using Firebug, I didn’t realize that console.log took a format string? I know, it’s right there in the docs, but did I ever read them? :-)