You're trying to put a text node inside an input element.
Input elements are empty and can't have children.
...
var checkbox = document.createElement('input');
checkbox.type = "checkbox";
checkbox.name = "name";
checkbox.value = "value";
checkbox.id = "id";
var label = document.createElement('label')
label.htmlFor = "id";
label.appendChild(document.createTextNode('text for label after checkbox'));
container.appendChild(checkbox);
container.appendChild(label);
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