Add type definitions for TypeScript

Author: forabi

index.d.ts

@@ -0,0 +1,60 @@
+declare module 'react-intersection-observer' {
+  import * as React from 'react';
+
+  export type IntersectionObserverProps = {
+    /** Children should be either a function or a node */
+    children: JSX.Element | null | ((inView: boolean) => JSX.Element | null);
+
+    /**
+     * The `HTMLElement` that is used as the viewport for checking visibility of
+     * the target.
+     * Defaults to the browser viewport if not specified or if `null`.
+     */
+    root?: HTMLElement;
+
+    /**
+     * Unique identifier for the root element - This is used to identify the
+     * `IntersectionObserver` instance, so it can be reused.
+     * If you defined a root element, without adding an `id`, it will create a new
+     * instance for all components.
+     */
+    rootId?: string;
+
+    /**
+     * Margin around the root.
+     * Can have values similar to the CSS margin property,
+     * e.g. `"10px 20px 30px 40px"` (top, right, bottom, left).
+     */
+    rootMargin?: string;
+
+    /**
+     * Element tag to use for the wrapping component
+     * @default `'div'`
+     */
+    tag?: string;
+
+    /** Number between 0 and 1 indicating the the percentage that should be
+     * visible before triggering. Can also be an array of numbers, to create
+     * multiple trigger points.
+     * @default `0`
+     */
+    threshold?: number;
+
+    /**
+     * Only trigger this method once
+     * @default `false`
+     */
+    triggerOnce?: boolean;
+
+    /** Call this function whenever the in view state changes */
+    onChange?(inView: boolean): void;
+
+    /** Use `render` method to only render content when inView */
+    render?(): JSX.Element | null;
+  };
+
+  export default class IntersectionObserver extends React.Component<
+    IntersectionObserverProps,
+    {}
+  > {}
+}