Javascript alternative for ruby, python's formatted string

formatted-string.js

/**
* Formatted string in javascript
*/

function renderTemplate (template, obj) {
  return template.replace(/\{\{[a-zA-Z]+\}\}/g, function (m) {
    for (var key in obj) {
      if (m.indexOf(key) !== -1) {
        return obj[key];
      }
    }
  });
}

console.log(renderTemplate("{{a}} {{b}}", {a: 'hello', b: 'world'}));