The Javascript String Object

The post below describes a primitive wrapper, which do not act like primitives and will always resolve to true. Please use with caution!

In the previous post, I mentioned that I am using Bash far less frequently as my work generally involves fewer server-related tasks and more business process type workflows. This generally means that my Javascript (by way of Google Apps Script) abilities have moved from “How do I do this?” to “How do I do this better!” In the past this led me to fleshing out the nuances of command line scripting (e.g. my post about reading files without cat), but JavaScript offers much deeper depths to plumb, many of which I have only discovered in passing.

One particular aspect of JavaScript objects has always bothered me: how do I use an object in a way that allows me to return a default value while still allowing access to properties contained within. Until today, I had assumed this wasn’t possible, and I was trying to bring too much of my Bash-oriented brain to this relatively new-to-me langauge. However, looking through Stackoverflow I discovered a method that met my perhaps non-standard needs.

      /*
Add object methods/values to a string while 
retaining the original value. From Stack Overflow
https://unforswearing.com/shorten/?KRn
*/

function addPropertiesToString() {
  var str = 'hello';

  // create string object
  str = new String(str);

// add object properties
// repeat() is available per MDN, but not Google Apps Script
// see MDN: https://unforswearing.com/shorten/?ywk

str.repeat = function(x) {
  var r = '';
  for (var q = 0; q < x; q++) { r=r + str; } return r; }; 
    // prepend text to str str.prepend=function(text) { 
    var wpre=text + str; return wpre; 
  }
    
  // a different hello 
  str.alternate='howdy' ; 
  
  // Logs for the methods above:
  
  console.log(str.repeat(3)); 
  // [17-09-19 17:34:46:698 EDT] hellohellohello 

  console.log(str.prepend('someone said: '));      
  // [17-09-19 17:34:46:699 EDT] someone said: hello

  console.log(str.alternate);
  // [17-09-19 17:34:46:699 EDT] howdy

  // And accessing the original str value
  console.log(str);

  // [17-09-19 17:34:46:700 EDT] hello     
}

In the above example, logging htmlMessage by itself would return the original string, which could be used elsewhere in the script (as part of a generated PDF, for example).

While this doesn’t save much time or increase productivity, it does keep the email scoped to the htmlMessage and with a few additional lines of code, an emailHtmlMessage class could be created to generate this type of object on the fly.

This was a fun exercise and my first real foray into deeper JavaScript methods/practices. Get in touch if you have any comments or suggestions!