bind-string.js

/**
 * Regular expressions of the delimiters.
 * @type {Array<string>}
 */
var DELIMS = ['%', '%'];

/**
 * Replaces all occurences of {<key>} with parameters[key]. When an
 * appropriate property of parameters is not found, omits the substitution.
 *
 * This function supports nested parameters (eg. weather.cloudy)
 * 
 * @param {string} string - The source string
 * @param {Object} parameters - A dict of parameters
 * @return {string}
 */
function bindString(string, parameters) {
  var re = new RegExp(DELIMS[0] + '([a-z0-9_]+(?:\.[a-z0-9_]+)*)' + DELIMS[1], 'gi');

  return string.replace(re, function(match, path) {
    path = path.split('.');
    var replacement = parameters;

    while (path.length && replacement !== undefined) {
      replacement = replacement[path[0]];
      path.shift();
    }

    return (replacement === undefined ? match : replacement);
  });
}