never-matching-regexp.coffee

dupStr = (str, n) -> (str for _ in [1..n]).join('')

testRegexp = (r, str, cnt) ->
    startTime = + new Date()
    for _ in [1..cnt]
        throw new Error("#{r} has matched!!") if str.match r 
    finishTime = + new Date()
    
    finishTime - startTime

tested_regexps = [/$^/, /^(?!.)./, /^(?!)/, /$a/, /$./, /(?!.)./, /(?!)/]
for reg in tested_regexps
    document.write "<h2>About: #{reg}</h2>"
    for len in [0, 10000, 20000, 30000]
        str = dupStr('.', len)
        for repeated_count in [1000]
            document.write """
            <p>
                length: #{ len },
                repeated_count: #{ repeated_count }:
                <strong>#{ testRegexp reg, str, repeated_count }</strong> (msec)
            </p>
                """

Referenced in this article: http://knjname.hateblo.jp/entry/2014/03/19/024810