Missing key bug
HTML
<script src="https://cdnjs.cloudflare.com/ajax/libs/handlebars.js/4.0.5/handlebars.js"></script>
<div id="output">
</div>
<script type="template/handlebars" id="template">
<p>Top level Foo: {{top_level_foo}}</p>
<p>Top level Bar (missing): {{top_level_bar}}</p>
<p>Nested.foo: {{nested.foo}}</p>
<p>nested.bar (missing): {{nested.bar}}</p>
</script>
JavaScript
Handlebars.registerHelper("helperMissing", function(context, options) {
console.error(`Missing key ${context.name}`);
return "MIA"
});
var template = Handlebars.compile(document.getElementById('template').innerHTML);
document.getElementById('output').innerHTML = template({
top_level_foo: "Foo",
nested: {
foo: "foo",
}
});