Created
March 15, 2014 14:15
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| #!/usr/bin/env ruby | |
| require "sinatra" | |
| include Math | |
| # Anything but a space, number, .+-*/ or ^ is dissallowed | |
| WHITELIST = %r{[^ 0-9.+\-*\/\^]+} | |
| html = <<-EOT | |
| <html> | |
| <head> | |
| <style> | |
| #expression { width: 100%, font-size 3em; display: block; margin-bottom: 1em; } | |
| </style> | |
| </head> | |
| <body> | |
| <input id="expression" placeholder="1+2"/> | |
| <div id="result"><div> | |
| <script src="http://code.jquery.com/jquery-1.11.0.min.js"></script> | |
| <script> | |
| $('#expression').keyup(function(){ | |
| $.get('/calc',{ | |
| exp:$('#expression').val() | |
| }, function(r){ | |
| $('#result').html(r); | |
| }); | |
| }); | |
| </script> | |
| </body></html> | |
| EOT | |
| get '/' do | |
| html | |
| end | |
| get '/calc' do | |
| begin | |
| eval(params['exp'].gsub(WHITELIST, '')).to_s | |
| rescue | |
| 'Invalid expression' | |
| end | |
| end |
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