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sebastien-p/LICENSE.txt

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Created August 24, 2011 16:13
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base62 encode
Raw
annotated.js
function (
a, // positive base10 encoded integer
b, // placeholder for result
c // placeholder for modulo
) {
for (
a = a !== +a || a % 1 ? -1 : a, b = ""; // if not a base10 integer, 'a' will be '-1'
// for example, '.5 % 1 == .5' but '1 % 1 == 0'
a >= 0; // also prevents the user to use negative base10 integers
a = Math.floor(a / 62) || -1 // using a bitwise hack here will fail with great numbers
)
// a%62 -> 0-61
// 0-9 | 36-61 | 10-35
// 48-57 | 65-90 | 97-121
// 0-9 | A-Z | a-z
b = String.fromCharCode(((c = a % 62) > 9 ? c > 35 ? 29 : 87 : 48) + c) + b;
return b // will return either an empty or a base62-encoded string
}
Raw
index.js
function(a,b,c){for(a=a!==+a||a%1?-1:a,b="";a>=0;a=Math.floor(a/62)||-1)b=String.fromCharCode(((c=a%62)>9?c>35?29:87:48)+c)+b;return b}
Raw
LICENSE.txt
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.
Raw
package.json
{
"name": "base62 encode",
"description": "A JavaScript implementation of base62 encode.",
"keywords": [
"base62",
"encode",
"integer",
"number",
"string"
]
}
Raw
test.html
<!DOCTYPE html>
<title>Foo</title>
<div>Expected value: <b>140bytes</b></div>
<div>Actual value: <b id="ret"></b></div>
<script>
var base62encode = function(a,b,c){for(a=a!==+a||a%1?-1:a,b="";a>=0;a=Math.floor(a/62)||-1)b=String.fromCharCode(((c=a%62)>9?c>35?29:87:48)+c)+b;return b};
document.getElementById("ret").innerHTML = base62encode(3748986303764)
</script>
@sebastien-p
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Working on a much more solid version...

function(a,b,c){for(a=a===+a&&/^\d+$/.test(a)&&a,b="";Math.floor(a);a/=62)b=String.fromCharCode(((c=a%62)>9?c>35?29:87:48)+c)+b;return b||"0"}

And also on decode : https://gist.github.com/1170594

@jed
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jed commented Aug 25, 2011

very nice work, @sebastien-p.

@sebastien-p
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@jed : thank you :)

@sebastien-p
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New version is here ! Still 4 bytes to go, help appreciated :)

@atk
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atk commented Aug 31, 2011

Simple: instead of a-=a!==+a|/-|\./.test(a)&&{} use a=a>=0&&a|0===a?a:NaN, which is 7 bytes shorter, but essentially does the same.

@sebastien-p
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@atk : a=a>=0&&a|0===a?a:NaN is great but if 'a' is 'true' it won't be 'NaN'. So I think a=a>=0&&~~a===a?a:-1 is what I need here. Thank you :)

EDIT : ~~a===a also fails with great numbers, for example ~~3748986303764 returns -520145644.

@atk
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atk commented Aug 31, 2011

We only got JS integers in any case, so the other part would fail if it wasn't serialized.

@sebastien-p
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Yeehaa, finally a = a !== +a || a % 1 ? -1 : a and a >= 0 did the trick !

135 bytes including input value validation and support for great numbers :)

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