Java-script strtr — translate characters or replace substrings

strtr.js

/**
* strtr() for JavaScript
* Translate characters or replace substrings
*
* @author Dmitry Sheiko 
* @version strtr.js, v 1.0.1 
* @license MIT
* @copyright (c) Dmitry Sheiko http://dsheiko.com
**/

String.prototype.strtr = function ( dic ) { 
    const str = this.toString(),
          makeToken = ( inx ) => `{{###~${ inx }~###}}`,
          
          tokens = Object.keys( dic )       
            .map( ( key, inx ) => ({
              key,
              val: dic[ key ],
              token: makeToken( inx )
            })),
              
          tokenizedStr = tokens.reduce(( carry, entry ) => 
            carry.replace( entry.key, entry.token ), str );
            
    return tokens.reduce(( carry, entry ) => 
            carry.replace( entry.token, entry.val ), tokenizedStr );
};

// Test
console.log("{palceholder}, I said hello".strtr({
    "{palceholder}" : "Molly",     
    "hello" : "grüß dich"
}));
console.log("{palceholder}, I said hello".strtr({
    "{palceholder}" : "hello",     
    "hello" : "grüß dich"
}));