wp-calypso/client/state/comments/constants.js

export const NUMBER_OF_COMMENTS_PER_FETCH = 50;

export const PLACEHOLDER_STATE = {
	PENDING: 'PENDING',
	ERROR: 'ERROR',
};

// values conveniently also correspond to css classNames to apply
export const POST_COMMENT_DISPLAY_TYPES = {
	singleLine: 'is-single-line',
	excerpt: 'is-excerpt',
	full: 'is-full',
};