angular filter that replaces a suffix with another

replace.js

// replace the file pointed at
angular.module('vendorApp')
  .filter('replace', function () {
    'use strict';

    // check if str ends with suffix
    function endsWith(str, suffix) {
      return str.indexOf(suffix, str.length - suffix.length) !== -1;
    }

    // take suffix off of str if str ends with suffix
    // return the string otherwise
    function trimSuffix(str, suffix) {
      if (endsWith(str, suffix)) {
        return str.slice(0, -(suffix.length));
      } else {
        return str;
      }
    }

    // 'path/to/img.jpg' | replace:'img.jpg':'orig_img.jpg'
    // replace defaults to 'photo.jpg'
    // withStr defaults to 'original_photo.jpg'
    return function (imagePath, replace, withStr) {
      if (!imagePath) { return imagePath; }

      replace = replace || 'photo.jpg';
      withStr = withStr || 'original_photo.jpg';

      // '#'s are added to the ends of image paths to trigger
      // ngSrc to reload the image. This strips them off.
      while (endsWith(imagePath, '#')) {
        imagePath = trimSuffix(imagePath, '#');
      }

      if (!endsWith(imagePath, replace)) {
        return imagePath;
      }

      return trimSuffix(imagePath, replace) + withStr;
    };
  });