How Do You Map-replace Characters In Javascript Similar To The 'tr' Function In Perl?

I've been trying to figure out how to map a set of characters in a string to another set similar to the tr function in Perl. I found this site that shows equivalent functions in J

Solution 1:

There isn't a built-in equivalent, but you can get close to one with replace:

data = data.replace(/[\-_]/g, function (m) {
    return {
        '-': '+',
        '_': '/'
    }[m];
});

Solution 2:

Method:

String.prototype.mapReplace = function(map) {
    var regex = [];
    for(var key in map)
        regex.push(key.replace(/[\-\[\]\/\{\}\(\)\*\+\?\.\\\^\$\|]/g, "\\$&"));
    returnthis.replace(newRegExp(regex.join('|'),"g"),function(word){
        return map[word];
    });
};

A perfect example:

var s = "I think Peak rocks!"
s.mapReplace({"I think":"Actually","rocks":"sucks"})
// console: "Actually Peak sucks!"

Solution 3:

I can't vouch for 'efficient' but this uses a regex and a callback to provide the replacement character.

functiontr( text, search, replace ) {
    // Make the search string a regex.var regex = RegExp( '[' + search + ']', 'g' );
    var t = text.replace( regex, 
            function( chr ) {
                // Get the position of the found character in the search string.var ind = search.indexOf( chr );
                // Get the corresponding character from the replace string.var r = replace.charAt( ind );
                return r;
            } );
    return t;
}

For long strings of search and replacement characters, it might be worth putting them in a hash and have the function return from that. ie, tr/abcd/QRST/ becomes the hash { a: Q, b: R, c: S, d: T } and the callback returns hash[ chr ].

Solution 4:

This functions, which are similar how it's built in Perl.

functions(a, b){ $_ = $_.replace(a, b); }
functiontr(a, b){ [...a].map((c, i) =>s(newRegExp(c, "g"), b[i])); }

$_ = "Εμπεδοκλης ο Ακραγαντινος";

tr("ΑΒΓΔΕΖΗΘΙΚΛΜΝΟΠΡΣΤΥΦΧΩ", "ABGDEZITIKLMNOPRSTIFHO");
tr("αβγδεζηθικλμνοπρστυφχω", "abgdezitiklmnoprstifho");
s(/Ξ/g, "X"); s(/Ψ/g, "Ps");
s(/ξ/g, "x"); s(/ψ/g, "Ps");
s(/ς/g, "s");

console.log($_);

Solution 5:

This will map all as to b and all y to z

var map = { a: 'b', y: 'z' };
var str = 'ayayay';

for (var i = 0; i < str.length; i++)
    str[i] = map[str[i]] || str[i];

EDIT:

Apparently you can't do that with strings. Here's an alternative:

var map = { a: 'b', y: 'z' };
var str = 'ayayay', str2 = [];

for (var i = 0; i < str.length; i++)
    str2.push( map[str[i]] || str[i] );
str2.join('');