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 1.0.2 
* @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( new RegExp( entry.key, "g" ), entry.token ), str );
          
  return tokens.reduce(( carry, entry ) => 
          carry.replace( new RegExp( entry.token, "g" ), 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"
}));

this only replace each pair of words once

@SnowyYANG You're right. I updated the snippet.