donphan/app/javascript/hooks/useRenderSignal.ts

33 lines
695 B
TypeScript

// This hook allows a component to signal that it's done rendering in a way that
// can be used by e.g. our embed code to determine correct iframe height
let renderSignalReceived = false;
type Callback = () => void;
let onInitialRender: Callback;
export const afterInitialRender = (callback: Callback) => {
if (renderSignalReceived) {
callback();
} else {
onInitialRender = callback;
}
};
export const useRenderSignal = () => {
return () => {
if (renderSignalReceived) {
return;
}
renderSignalReceived = true;
if (typeof onInitialRender !== 'undefined') {
window.requestAnimationFrame(() => {
onInitialRender();
});
}
};
};