I ran into this in an existing Angular project where I have an Input named itemType in an Angular directive. Prettier transforms my itemType attribute into itemtype since I'm applying it to a div element and itemtype is a known global attribute. However, this breaks the binding with the Angular Input in the directive.

This type of transformation is likely always unsafe in the Angular world, even if there is no noticeable directive being applied to the element, since I can have a directive with a generic selector such as div and custom Inputs on it.

For now I'm using Angular's square bracket notation: [itemType]="'x'". This might even be the best option (since it avoids conflicts with the native itemtype attribute). However, Prettier should probably not break user-code, so I'd qualify this as a bug.

Prettier 1.15.2
Playground link

--parser angular

Input:

<div someDirective itemType="x"></div>

Output:

<div someDirective itemtype="x"></div>

Expected behavior (unchanged):

<div someDirective itemType="x"></div>