JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://dl.dropboxusercontent.com/s/1iu4c1zmp4mz4md/handlebars.js"></script>
<h2>Subexpressions bug</h2>

<div>
    <strong>Version:</strong>
    <span id="version"></span>
</div>

<br />
<div><strong>Result:</strong></div>
<div id="result"></div>

<br />
<div><strong>Expected:</strong></div>
<div id="expected"></div>

JavaScript

var string = '{{input aria-label=(t item.field) placeholder=(t item.placeholder)}}';

var context = {
  item: {
    field: "Name",
    placeholder: "Example User"
  } 
};

var helpers = {
  input: function(options) {
    var hash        = options.hash;
    var ariaLabel   = Handlebars.Utils.escapeExpression(hash['aria-label']);
    var placeholder = Handlebars.Utils.escapeExpression(hash.placeholder);
    return new Handlebars.SafeString('<input aria-label="' + ariaLabel + '" placeholder="' + placeholder + '" />');
  },
  t: function(defaultString) {
    return new Handlebars.SafeString(defaultString);
  }
};



Handlebars.registerHelper('input', helpers.input);
Handlebars.registerHelper('t', helpers.t);

var template = Handlebars.compile(string);
var expected = '<input aria-label="Name" placeholder="Example User" />';


document.getElementById('version').innerText += Handlebars.VERSION;
document.getElementById('result').innerText += template(context);
document.getElementById('expected').innerText += expected;