AllAccepted answers
Eduard Lebedyuk · Aug 30, 2019

You're right, I need to change $replace with Ш to $replace with Щ. Ш is replaced in $translate anyway

ClassMethod convertRussionToEnglish4(russian = "привет") As %String [ CodeMode = expression ]
{
$tr($zcvt($replace($replace($tr(russian, "абвгдезийклмнопрстуфхыэАБВГДЕЗИЙКЛМНОПРСТУФХЫЭЖЦЧШЮЯжцчшюяьЬъЪ", "abvgdeziyklmnoprstufhyeABVGDEZIYKLMNOPRSTUFHYE婨味䍨卨奵奡穨瑳捨獨祵祡"),"щ","shch"),"Щ","Shch"),"O","UnicodeBig"),$c(0))
}
Eduard Lebedyuk · Aug 29, 2019

Here's my new one-liner. Now 6 times faster.

ClassMethod convertRussionToEnglish4(russian = "привет") As %String [ CodeMode = expression ]
{
$tr($zcvt($replace($replace($tr(russian, "абвгдезийклмнопрстуфхыэАБВГДЕЗИЙКЛМНОПРСТУФХЫЭЖЦЧШЮЯжцчшюяьЬъЪ", "abvgdeziyklmnoprstufhyeABVGDEZIYKLMNOPRSTUFHYE婨味䍨卨奵奡穨瑳捨獨祵祡"),"щ","shch"),"Ш","Sh"),"O","UnicodeBig"),$c(0))
}

Here's tests:

do ##class(Test.Cyr).Time()
Method: convertRussionToEnglish1, time: .009022 <- original
Method: convertRussionToEnglish2, time: .000689 <- my first idea
Method: convertRussionToEnglish3, time: .000417 <- Evgeny
Method: convertRussionToEnglish4, time: .000072 <- this version
Method: convertRussionToEnglish5, time: .000124 <- Jon
 
Compete code
Eduard Lebedyuk · Aug 29, 2019

Less searching all around:

ClassMethod getDict(Output dict)
{
    kill dict
    set dict("а")="a"
    set dict("б")="b"
    set dict("в")="v"
    set dict("г")="g"
    set dict("д")="d"
    set dict("е")="e"
    set dict("ж")="zh"
    set dict("з")="z"
    set dict("и")="i"
    set dict("й")="y"
    set dict("к")="k"
    set dict("л")="l"
    set dict("м")="m"
    set dict("н")="n"
    set dict("о")="o"
    set dict("п")="p"
    set dict("р")="r"
    set dict("с")="s"
    set dict("т")="t"
    set dict("у")="u"
    set dict("ф")="f"
    set dict("х")="kh"
    set dict("ц")="ts"
    set dict("ч")="ch"
    set dict("ш")="sh"
    set dict("щ")="shch"
    set dict("ъ")=""
    set dict("ы")="y"
    set dict("ь")=""
    set dict("э")="e"
    set dict("ю")="yu"
    set dict("я")="ya"
}

/// w ##class(Test.Cyr).convertRussionToEnglish()
ClassMethod convertRussionToEnglish(word As %String = "Привет")
{
    do ..getDict(.dict)
    set out = ""
    for i=1:1:$l(word) {
        set letter = $e(word, i)
        set letterL = $zcvt(letter, "l")
        set outLetter = dict(letterL)
        set:letter'=letterL outLetter = $zcvt(outLetter, "U")
        set out = out _ outLetter
    }
    quit out
}
Eduard Lebedyuk · Aug 23, 2019

In jQuery you don't need Allow* headers.

On server try this for TESTING ONLY:

Do %response.SetHeader("Access-Control-Allow-Origin",..GetOrigins())
Do %response.SetHeader("Access-Control-Allow-Credentials","true")
Do %response.SetHeader("Access-Control-Allow-Methods","GET, PUT, POST, DELETE, OPTIONS")
Do %response.SetHeader("Access-Control-Max-Age","10000")
Do %response.SetHeader("Access-Control-Allow-Headers","Content-Type, Authorization, Accept-Language, X-Requested-With")

And GetOrigins

/// Get Origin from %request object
ClassMethod GetOrigins() As %String
{
    set url = %request.GetCgiEnv("HTTP_REFERER")
    return $p(url,"/",1,3) // get http(s)://origin.com:port
}