JS function to extract variables from template string

extract_vars.js

function extract_vars(template, openChar, closeChar) {
  openChar = openChar || '{';
  closeChar = closeChar || '}';
  
  var i = 0;
  var data = [];
  
  do { 
    if (template[i] == '{') {
      for (var j=i+1; j<template.length; j++) {
        if (template[j] == '}') {
          data[data.length] = template.slice(i+1, j);
          i = j+1;
          break;
        }
      }
    }
  } while (++i < template.length);

  return data;
}

function parse_vars(vars, delimiter) {
  delimiter = delimiter || ':';
  
  return vars.map(function(item) {
    var a = item.split(delimiter);
    return { name: a[0], default: a[1] };
  });
}

var aa = extract_vars("The {adj} {color:brown} fox jumps over the lazy {animal:dog}.");
console.log(aa);

var vars = parse_vars(aa);

console.log(vars);

console.log(vars[0].default ? 'has default' : 'no default');