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base62 encode
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
}
function base62(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}
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}
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 encode",
"description": "A JavaScript implementation of base62 encode.",
"keywords": [
"base62",
"encode",
"integer",
"number",
"string"
]
}
<!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>
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