/**
 * Equivalent to Lit's "nothing", but has type "never" to allow it to be set as a
 * value for any JSX attribute.
 *
 * By default in Lit, nullish attribute value renders to an attribute without a
 * value (which is interpreted by HTML as "true"). To tell Lit that you don't
 * want the attribute to be present, use the `nothing` value.
 *
 * @example
 * ```tsx
 * <a href={this.href ?? nothing}>{this.label}</a>
 * ```
 *
 * @remarks
 * This is not a concern for properties as they are passed as is without
 * serialization. For this reason, during _JSX to lit-html_ conversion, most JSX
 * props are converted properties, except for the few cases when an attribute
 * has no equivalent property.
 */
export declare const nothing: never;
/**
 * A sentinel value that signals that a value was handled by a directive and
 * should not be written to the DOM.
 *
 * @remarks
 * This is equivalent to Lit's native "noChange", but has type "never" to allow
 * it be set as a value for any JSX attribute.
 */
export declare const noChange: never;
/**
 * Like native element.setAttribute(), but instead of stringifying nullish
 * values, will call element.removeAttribute()
 */
export declare function setAttribute(element: Element, attributeName: string, value: unknown): void;
/**
 * If you have a property that can be both of string or boolean type, there is
 * no automatic boolean conversion in place - that means the attribute is
 * treated as a string.
 *
 * This converter improves that handling by converting `true` property value to
 * an empty attribute, and `false` to removing the attribute.
 *
 * When setting the boolean attribute, the value is still not parsed (and will
 * be either `null` or `""`). This matches the behavior in Stencil.
 *
 * ```tsx
 * @property({ reflects:true, converter: stringOrBoolean }) icon: string | boolean;
 * // ...
 * this.icon = false;  // attribute is removed
 * this.icon = true;  // attribute is ""
 * this.icon = "name";  // attribute is "name"
 * ```
 */
export declare const stringOrBoolean: {
    toAttribute: (value: unknown) => string | null;
};