Does has-icon any effect in buttons?

[neoacevedo]

Does actyally have the property has-icon any effect in buttons with icon?

My guess is no. Going to the documentation and seeing the examples, the icon in each button is anyway rendered despite this property is present or not.

<md-filled-tonal-button>
  Send
  <svg slot="icon" viewBox="0 0 48 48"><path d="M6 40V8l38 16Zm3-4.65L36.2 24 9 12.5v8.4L21.1 24 9 27Zm0 0V12.5 27Z"/></svg>
</md-filled-tonal-button>

<md-text-button trailing-icon>
  Open
  <svg slot="icon" viewBox="0 0 48 48"><path d="M9 42q-1.2 0-2.1-.9Q6 40.2 6 39V9q0-1.2.9-2.1Q7.8 6 9 6h13.95v3H9v30h30V25.05h3V39q0 1.2-.9 2.1-.9.9-2.1.9Zm10.1-10.95L17 28.9 36.9 9H25.95V6H42v16.05h-3v-10.9Z"/></svg>
</md-text-button>

[asyncliz]

Yes, but it's only necessary for Server Side Rendering (SSR) to avoid a Flash Of Unstyled Content (FOUC).

Buttons will automatically add the has-icon attribute, which changes the padding style of the button. However, if they do not initially have the attribute when SSR'd, the padding will "flash" briefly as it changes once JavaScript hydrates the button and adds the missing attribute.

If you are not SSR-ing components, you do not need to worry about adding any has-* attributes.