Today I Learned

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Wrap A ReasonReact Component For Use In JavaScript

Consider the following ReasonReact component for displaying a greeting.

let component = ReasonReact.statelessComponent("Hello");

let make = (~name, _children) => {
  ...component,
  render: _self =>
    <p> {ReasonReact.string("Hello, ")} {ReasonReact.string(name)} </p>,
};

If we will just be using this component in a ReasonML context, then that is all we need.

If we want this component available for use in a JavaScript file, we have a little more work to do. We need to define the shape of the component’s props using a bucklescript directive and then wrap the component so that it gets appropriate exported for a JavaScript context.

Here is what that looks like.

[@bs.deriving abstract]
type jsProps = {name: string};

let default =
  ReasonReact.wrapReasonForJs(~component, jsProps =>
    make(~name=jsProps->nameGet, [||])
  );

Our only prop is name which is a string. The wrapReasonForJs function and accompanying binding to default mean that we can import the compiled JS-equivalent like so:

import Hello from 'src/components/Hello.bs.js';

See the docs for more details on Reason/JS interop.