Typings: cannot construct legacy elements with properties defined only with type

[jlaamanen]

Description

Unable to use legacy Polymer element constructor when using shorthand property definitions (i.e. only giving the property type instead of metadata object).

Steps to Reproduce

Try to create an element:

Polymer({
  is: "my-element",
  properties: {
    foo: Number,
    bar: {
      type: Number
    }
  }
});

Expected Results

No errors

Actual Results

There will be an error:

[ts]
Argument of type '{ is: string; properties: { foo: NumberConstructor; bar: { type: NumberConstructor; }; }; }' is not assignable to parameter of type 'PolymerInit'.
  Types of property 'properties' are incompatible.
    Type '{ foo: NumberConstructor; bar: { type: NumberConstructor; }; }' is not assignable to type 'PolymerElementProperties'.
      Property 'foo' is incompatible with index signature.
        Type 'NumberConstructor' has no properties in common with type 'PolymerElementPropertiesMeta'.

If foo property is removed or defined with a metadata object, the error will disappear.

Browsers Affected

All

Versions

• Polymer: v2.6.0

There is a fast and simple fix for this issue: add | Function to property type. I will be posting a PR about this shortly.