Friday, May 27, 2011

My Last Comments On JSLint


I have been working with many teams and I have used JSLint on daily basis. This post is not about the tool itself, neither against Douglas work, this post is about developers often too religious about this tool.
Finally, if you follow this blog you have already read tons of other reasons to think rather than "suffer silently this tool".
It's my last post about it and I hope "it will not hurt your feelings".

Seriously guys, it's not that I think JSLint is all bad, but I cannot stop thinking it's simply an effect.
The more I hear or read about developers being so religious about this tool, the more I feel to blame it.
I am pretty sure Douglas will hate me for this post but I really hope he will read it 'till the end.

Douglas Talk At Falsy Values

Both me and big Doug were there, me for a workshop and Mr D. for his speech.
"Surprisingly" Mr Crockford talked about JSLint (again?!) and why it's so good.
While many hints for newcomers are absolutely a must know, many others are absolutely inconsistent for senior JavaScript developers.
There is a particular slide and a particular sentence Douglas said there:
... write code the way it's meant for the language ...

Above sentence was related to variables declaration, showing behind something similar to this classic example:

(function () {
// never executed
if (false) {
var something = 123;

As all of us know, and if not we should, the reason JSLint would like to have all variables defined on top of the function is that no matter which condition, for or while loop, we have at some point, the parser will pre-consider all var in the same scope as local scope variables available since the very beginning.

(function () {
// there is no "var" in this scope
// throws "Can't find variable: something"
if (false) {
// eventually global in ES3 and ES5 with no strict
something = 123;

The moment we define a variable local, even if we never reach that line, that variable is available for the whole scope, got it?

(function () {
// undefined and no errors
if (false) {
var something = 123;

Good, now ...

JSLint Inconsistencies

Since the previous point is clear to everybody, I wonder if it's clear that function declaration has even more precedence than variables.

(function () {
// the function declared later on

function something() {
return 123;

This is not true for function expressions, where the result will still be the same obtained with variables:

(function () {
// undefined and no errors

var something = function() {
return 123;

Accordingly, function declaration is referenced on top of everything, variables included!
So why on bloody earth this piece of code does not pass JSLint?

var something = (function () {

// top reference available ever
// function declaration
function something() {
return oneTwoThree;

// second references available in this scope
// local scope variable
var oneTwoThree = 123;

// return the local function call
return something();


Try by yourself the result:

Implied global: oneTwoThree 5

Unused variable: oneTwoThree 1 'something'


Global something

1 'something'()
Unused oneTwoThree
Complexity 1

4 something()
Global oneTwoThree
Complexity 1

I can bet the amount of bullshit I can read in latter result is a shame for Douglas Crockford in first person, isn't it?

Not Only Inconsistencies

Another part covered by Doug speech was the with statement ... here summarize:

... somebody (n.d. I guess me) may argue that the with statement may be useful in certain situations, but since it is always ambiguous and there is nothing that could not be done without it, the with statement should disappear from JavaScript ....
... and this is what happened.
If we try "use strict"; activation in most recent browsers we can spot that the with statement is not allowed anymore, "thanks"!

A Tool To Rule Them All

It was actually a colleague of mine asking Douglas this question (or what I got about it) :

... so, you are saying that JS developers have no discipline, but don't you think that "dictating discipline" is not such easy task as well? ...
I honestly do not remember the answer but I am sure Douglas provided a proper one ... anyway ... what I do believe is that every developer has is own style, as long as syntax and readability are not too much compromised.
If we use this tool thinking our code will improve any how we are first of all acting like machines plus we are not considering a "little detail" ...

Your Team Does Not Know JavaScript

Precisely! I know this is hard to face, but in 11 years of JavaScript programming I have never found a reason to have such tool that changes allowed programming language syntax defined by specifications ... fucking read them and stop winging! (and pardon my french)
In few words, I have never had a single problem to understand any other piece of JavaScript code written by any possible developer out there but when I had a problem, and at the beginning of whatever programming language we all have, I have investigated, studied, and finally understood, what was going on in that piece of code and what was missing from my JS knowledge about it.
Surely I did not blame the other developer, since if we would like to be monkeys on daily basis, of course we should use as many tools as possible that throw warnings even if the piece of code we wrote is absolutely correct, and we still have my precedent example few paragraph before as proof ...
On the other hand, if we would like to master our JavaScript knowledge there is no way a piece of code that perfectly works could be screwed up because of JSLint.

Early JavaScript Days

When Douglas Crockford was still promoting JavaScript all over the world, nobody had any idea what he was talking about ... well, now we all have.
This bloody language is absolutely everywhere and those "feeling cool" Java developers that still think JS is a toy are regretting 50% of their studies because they just don't get it ... that's why projects like GWT exists: developers that think JavaScript is a toy, write Java that is gonna be translated into Javascript ... and this is how powerful and flexible JavaScript is.
In these days, and surely before, we truly need discipline and a lot of hints since as lazy developers we could not spend half a day reading ECMAScript 3rd Edition specs ... isn't it?
In these days, and for these developers, of course JSLint has to be there, they don't know what they are doing but hey, at least they are willing to learn something more from this tool (and most likely behind a syntax translator such GWT is, created to do not throw JSLint warnings ...) .
As demonstrated before, this is not enough.
Java skills into JavaScript language are similar to me pretendng to have Alex Martelli knowledge using Visual Basic 6 on daily basis ... I hope you know what I mean ...
As summary, if you think you can move knowledge from another programming language without deeply understanding the new one pretending you come from "something better" you are half way trough your own failure.
At the end of the day it may not matters, as long as the next point is clear for everybody.

TDD And Unit Tests Are The Only "Safer Way"

Yeah you read it right ... there is no way our JavaScript code is gonna be any safer because of JSLint or whatever JS validation tool: no fucking way!
If we think that === rather than == is all we need to be safe, without understanding why we may be safer or why we may do something simply redundant without considering cases where we want to ==, we have never been so wrong.
Unit Tests, and more Unit Tests on top of Unit Tests are the only answer to our code quality!
It does not matter how we write routines as long as real Senior Developers can understand it, simply asking more if they really don't, and as long as all our possible implementation cases have been considered.
If we are those kind of "my code pass JSLint, my code is better and safer and cleaner" develoeprs, we are simply demonstrating how much we still have to learn about programming.
I don't know any other language that religious or with need of these kind of "natural programming code evaluation tools" and we all know JavaSscript is not the first programming language ever, neither the last one.
If it's about some common code convention we don't need JSLint, we simply need a bloody wiki/web/infrastructure page able to explain it so that somebody else could eventually blame it the moment he's flexible enough to understand meant edge cases.
This is what I have answered as well during my workshop when somebody asked me what I think about JSLint, while the whole post is the reason I did not even start arguments or questions after Douglas speech, and the reason I will never do it.
We all have our style, Douglas has his own one, and I am happy for him he is that consistent.
Should I be a Douglas Crockford clone on daily basis? Hell no, since as I have said: I know WTF I am writing and why

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