angular/angular.js

@ngdoc error
@name $compile:missingattr
@fullName Missing required attribute
@description

This error may occur only when {@link $compileProvider#strictComponentBindingsEnabled `$compileProvider.strictComponentBindingsEnabled`} is set to `true`.

If that is the case, then all {@link $compileProvider#component component} controller bindings and
{@link $compileProvider#directive directive} scope / controller bindings that are non-optional,
must be provided when the directive is instantiated.

To make a binding optional, add '?' to the definition.

## Example:

```js

app.component('myTest', {
  bindings: {
    first: '=?', // optional
    second: '='
  },
  controller: function() {
    ...
  },
  template: '...'
});

```

This component will throw `missingattr` for the `second` binding when used as follows:

```html
<my-test></my-test>
```