dorey / javascript-equality-table Goto Github PK

hi dorey, take a look at this, the author reordered it so it looks more better.

I am writing a series of JS books called "You Don't Know JS", here:

https://github.com/getify/You-Dont-Know-JS

The next title, which I'm about to begin, is "Types & Grammar", and I wanted to know if you'd be willing to let me publish (with attribution, of course) an image-form of your chart(s) in the book?

The books are released CC-NC-ND 3.0 (free, non-commercial, non-derivative) online in that repo, and are then being published traditionally (print and ebook form) through O'Reilly.

If so, I'd be grateful, as I think it's a great visualization for the topic. Thanks for your time! :)

The Boolean object seem to get cast when using == but not when using ===.

ex.
new Boolean(true) == true // -> true
new Boolean(true) === true // -> false
new Boolean(false) == false // -> true
new Boolean(false) === false // -> false

What about adding 0and -0 ? It may have some special behavior in JavaScript (see https://twitter.com/creationix/status/449215561147219969).

NaN == NaN being false is very weird, but at least Infinity == Infinity is true! if()ing Infinity is also true, as is if(-Infinity).

The text above the columns should, in my opinion, no longer be generated with <canvas> tags. Instead, because CSS has the writing-mode property, it can be used. If set to vertical-rl, the text will be still rotated, but also accessible to screen readers.

A string such as " \t \n\n " is falsy and the fact that

"  \t  \n\n      " == false

is true would make a nice addition to the table.

Nice work on this by the way!

Object.is ships in some browsers, is part of ES6, and is another way to check for value equality (checks that two values are the same type and same value of that type): https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/is

The red and green used in the tables is not color blind safe. A color blind user can tell that there are two colors being used, but they can not tell which color is red and which color is green.

Something that I came up against recently, whitespace compared for equality with 0 resolves to true. It's not the same as an empty string because empty string and white space don't compare equally with empty array for example. So I think white space could legitimately be included in the table.

'\n\t ' == 0 true
'\n\t ' == [] false
'' == [] true

I noticed the unified table does not seem to show how IF statements work with the values. Am I just misreading it?

'0X0'
'1E0'
1E-1111
['Infinity']

'0X0' : string that is hex for zero if converted to Number
'1E0' : Exponential notation for one if converted to Number
1e-1111 : underflow (zero)
['Infinity'] : ['Infinity'] == Infinity

PS: Thanks for the grid, it is a great reminder of the evils of ==.

PPS: Not to mention 077 versus 088 (ouch - octal!).

PPPS: An == or === symbol inside the green cells of the grids made it clearer to me (using developer toolbar).

Both are false, however table shows it true.