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| function ( | |
| a, // base62 encoded string | |
| b, // placeholder for result | |
| c, // placeholder for iterator | |
| d // placeholder for char code | |
| ) { | |
| for ( | |
| b = c = ( // 'false - 1' will return '-1' and 'true - 1' will return '0' | |
| a === (/\W|_|^$/.test(a += "") || a) // tests if 'a' is a properly base62-encoded string and coerces it to one | |
| ) - 1; // so, 'b' and 'c' are initialized with either '-1' or '0' | |
| d = a.charCodeAt(c++); // if 'c' equals '-1', 'd' is 'NaN' which breaks the loop execution | |
| ) | |
| b = b * 62 + d - [, 48, 29, 87][d >> 5]; // See comments : https://gist.github.com/1170594#gistcomment-48129 | |
| return b // positive base10 integer or '-1' if 'a' is not a base62 encoded string | |
| } |
| function(a,b,c,d){for(b=c=(a===(/\W|_|^$/.test(a+="")||a))-1;d=a.charCodeAt(c++);)b=b*62+d-[,48,29,87][d>>5];return b} |
| DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE | |
| Version 2, December 2004 | |
| Copyright (C) 2011 Sebastien P. https://twitter.com/#!/_sebastienp | |
| Everyone is permitted to copy and distribute verbatim or modified | |
| copies of this license document, and changing it is allowed as long | |
| as the name is changed. | |
| DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE | |
| TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION | |
| 0. You just DO WHAT THE FUCK YOU WANT TO. |
| { | |
| "name": "base62 decode", | |
| "description": "A JavaScript implementation of base62 decode.", | |
| "keywords": [ | |
| "base62", | |
| "decode", | |
| "string", | |
| "number", | |
| "integer" | |
| ] | |
| } |
| <!DOCTYPE html> | |
| <title>Foo</title> | |
| <div>Expected value: <b>3748986303764</b></div> | |
| <div>Actual value: <b id="ret"></b></div> | |
| <script> | |
| var base62decode = function(a,b,c,d){for(b=c=(a===(/\W|_|^$/.test(a+="")||a))-1;d=a.charCodeAt(c++);)b=b*62+d-[,48,29,87][d>>5];return b}; | |
| document.getElementById("ret").innerHTML = base62decode("140bytes") | |
| </script> |
how about saving at least 1 byte with a===(/^[a-z\d]+$/i.exec(a)||0)[0] which should take care of empty strings? Or even shorter: a===(/\W|_|^$/.test(a)||a) in which we use the property of /^$/ to match empty strings?
@atk : thanks, base62 decode is now 4 bytes shorter :)
@sebastien-p: test coerces its argument to string, so a+='' has no function there. You may want to use a===(/\W|_|^$/.test(a)||a+'')
@atk : yep, I know, but a needs to be a string for a.charCodeAt(c++) to work, so I force coercion here on purpose.
For a not to be a string and to be coerced to a string that coerced into a valid base62 string, it would have to be an object with a toString method, so handling non-strings is rather pointless, isn't it?
@atk : you're right, input value validation is optional and the whole entry would be shorter without it. I added it because it fits and mostly because I needed the function to be designed this way.
true // -1
false // -1
I found this useful and converted it into C# if anyone ever needs it. Not intended to be 140 bytes small.
a === (/\W|_/.test(a += "") || a)could be great instead ofa === (a += "") && /^[a-z\d]+$/i.test(a)but sadly doesn't prevent passing an empty string as argument.