29 lines
1.2 KiB
JavaScript
29 lines
1.2 KiB
JavaScript
/**
|
|
* @internal
|
|
* Combine two event callbacks into a single callback function that calls each one in order.
|
|
*
|
|
* Usage example:
|
|
* ```ts
|
|
* state.slot.onChange = mergeCallbacks(state.slot.onChange, ev => {
|
|
* // Handle onChange
|
|
* });
|
|
* ```
|
|
*
|
|
* The primary use is to avoid the need to capture an existing callback (`state.slot.onChange` in the example) to a
|
|
* local variable before replacing with a new listener that calls the existing one. This helps avoid bugs like:
|
|
* * Infinite recursion by calling the re-assigned state.slot.onChange if it's not captured to a local variable.
|
|
* * Missing a call to the original onChange due to an early return or other conditional.
|
|
*
|
|
* If you need a callback that is stable between renders, wrap the result in {@link useEventCallback}.
|
|
*
|
|
* @param callback1 - The first callback to be called, or undefined
|
|
* @param callback2 - The second callback to be called, or undefined
|
|
*
|
|
* @returns A function that that calls the provided functions in order
|
|
*/ export function mergeCallbacks(callback1, callback2) {
|
|
return (...args)=>{
|
|
callback1 === null || callback1 === void 0 ? void 0 : callback1(...args);
|
|
callback2 === null || callback2 === void 0 ? void 0 : callback2(...args);
|
|
};
|
|
}
|