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I'm pretty sure there's not a better way to do this but figured it couldn't hurt to ask.

I'm tired of typing out a='abcdefghijklmnopqrstuvwxyz'.

Cool languages have Range('a'..'z') or similar

What can we come up with with JS that's as short as possible??

for(i=97,a='';i<123;){a+=String.fromCharCode(i++)}

is longer than just the alphabet - but guarantees I don't screw up somewhere.

I'm hoping there's a nasty bit-shifty way to produce a-z in less than 50 characters.

I messed around with i=97;Array(26).map(x=>String.fromChar....i++

but it was always way longer by the time I joined then split the array(26) to be useable


Edit: I've gotten it down to

[...Array(26)].reduce(a=>a+String.fromCharCode(i++),'',i=97)

60 bytes

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11  
@muddyfish, LuisMendo: This is on-topic per meta. – Doorknob Feb 9 at 21:11
1  
[...Array(26)].map((q,w)=>String.fromCharCode(w+97)) is 52 bytes and add another 7 for the .join`` – andlrc Feb 9 at 21:13
    
    
@dev-null a='';i=97;[...Array(26)].map(b=>a+=String.fromCharCode(i++)) is 60 but takes care of the join how are you doing join in 7 without getting commas in the result? – Charlie Wynn Feb 9 at 21:19
1  
@CharlieWynn [...Array(26)].map((q,w)=>String.fromCharCode(w+97)).join`` – andlrc Feb 9 at 21:23
up vote 7 down vote accepted

Alternative to String.fromCharCode

... if you are happy with a lowercase only alphabet.

for(i=9,a='';++i<36;)a+=i.toString(36) // 38, cannot be used in an expression
[...Array(26)].map(_=>(++i).toString(36),i=9).join`` // 52 directly returnig the string desired
[...Array(26)].map(_=>a+=(++i).toString(36),a='',i=9) // 53 assign to a variable
(i=9,[for(_ of Array(26))(++i).toString(36)].join``) // 52 ES7 direct return
i=9,a='',[for(_ of Array(26))a+=(++i).toString(36)] // 51 ES7 assign to a variable
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Oh dang, that is clever. So it's starting with 10, converting to base 36 and printing it? so a-z! – Charlie Wynn Feb 10 at 14:46

Note: All of these techniques assign the alphabet string to variable a.


I am 99% certain that the shortest way to achieve this in JavaScript is indeed:

a="abcdefghijklmnopqrstuvwxyz" // 30 bytes

But there are several other interesting methods. You can use string compression:

a=btoa`i·?yø!?9%?z)ª»-ºü1`+'yz' // 31 bytes; each ? represents an unprintable

You can get the compressed string from atob`abcdefghijklmnopqrstuvwx`. The 'yz' must be added manually because if you compress the whole string, while the result is only 27 bytes, it will turn out as abcdefghijklmnopqrstuvwxyw==.

I believe the shortest way to do it programmatically is also the method you suggested:

for(i=97,a='';i<123;)a+=String.fromCharCode(i++) // 48 bytes

You can do it with ES6 features (template strings ``, spread operator ...) if you want:

a=[...Array(26)].map(_=>String.fromCharCode(i++),i=97).join`` // 61 bytes
a=[...Array(26)].map((_,i)=>String.fromCharCode(i+97)).join`` // also 61 bytes
a=[...Array(i=26)].map(_=>String.fromCharCode(++i+70)).join`` // again, 61 bytes

You can do one better with a variable instead of .join``:

[...Array(26)].map(_=>a+=String.fromCharCode(i++),i=97,a='') // all 60 bytes
[...Array(26)].map((_,i)=>a+=String.fromCharCode(i+97),a='')
[...Array(i=26)].map(_=>a+=String.fromCharCode(++i+70),a='')

Or ES7 with array comprehensions, which is another byte shorter:

a=[for(_ of Array(i=26))String.fromCharCode(++i+70)].join`` // 59 bytes

Creating the variable beforehand saves yet another byte:

a='',[for(_ of Array(i=26))a+=String.fromCharCode(++i+70)] // 58 bytes

Also, String.fromCharCode accepts multiple arguments and will automatically join them. So we can golf each ES6 version down to 57 bytes:

a=String.fromCharCode(...[...Array(26)].map(_=>i++,i=97)) // all 57 bytes
a=String.fromCharCode(...[...Array(26)].map((_,i)=>i+97))
a=String.fromCharCode(...[...Array(i=26)].map(_=>++i+70))

And the ES7 one down to 55:

a=String.fromCharCode(...[for(_ of Array(i=26))++i+70]) // 55 bytes

If you'd like to learn more about golfing ranges, check out this set of tips. There's also one about ES7's array comprehensions.

EDIT: As edc65 has pointed out, most of these become shorter using i.toString(36) instead of String.fromCharCode(i):

for(i=9,a='';++i<36;)a+=i.toString(36) // 38 bytes
a=[...Array(26)].map(_=>(++i).toString(36),i=9).join`` // 54 bytes
[...Array(26)].map(_=>a+=(++i).toString(36),i=9,a='') // 53 bytes
i=9,a=[for(_ of Array(26))(++i).toString(36)].join`` // 52 bytes
i=9,a='',[for(_ of Array(26))a+=(++i).toString(36)] // 51 bytes

I believe this one is the shortest possible that can be called as a function return value:

eval("for(i=9,a='';++i<36;)a+=i.toString(36)") // 46 bytes

It's three bytes shorter than manually returning it from a function:

x=>eval("for(i=9,a='';++i<36;)a+=i.toString(36)") // 49 bytes
x=>{for(i=9,a='';++i<36;)a+=i.toString(36);return a} // 52 bytes

Of course, x=>"abcdefghijklmnopqrstuvwxyz" still beats everything else.

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I really like where this is going - just wish I could ES7 in chrome :( – Charlie Wynn Feb 9 at 21:42
2  
@CharlieWynn Yes, it's a shame that not all browsers support all the latest features. But after all, Chrome wasn't built in a day... ;) – ETHproductions Feb 9 at 21:53
    
Most of these solution can be shortened using .toString instead of String,.fromCharCode. See my answer – edc65 Feb 9 at 22:42
1  
@CharlieWynn I think Chrome Beta now supports all of ES7 and all of ES6 except modules and tail call optimisation. – gcampbell Jun 10 at 10:28

Here's another approach, a 51 byte ES6 expression:

String.fromCharCode(...Array(123).keys()).slice(97)

50 bytes in upper case of course.

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