Disable setImmediate event loop yielding in the browser, (#50)

* Disable `setImmediate` event loop yielding in the browser, Closes #48 * Apply suggestions from code review Co-Authored-By: Phil Plückthun <phil@kitten.sh> * Disable yielding in `visitLoop` in environments with no `setImmediate` Co-authored-by: Phil Plückthun <phil@kitten.sh>

Author: zenflow

src/index.js

@@ -2,7 +2,7 @@
 
 import React, { type Node, type Element } from 'react'
 import type { Visitor, YieldFrame, Frame, AbstractElement } from './types'
-import { visitChildren, resumeVisitChildren, update } from './visitor'
+import { visitChildren, resumeVisitChildren, update, SHOULD_YIELD } from './visitor'
 import { getChildrenArray } from './element'
 
 import {
@@ -51,14 +51,19 @@ const updateWithFrame = (
 ): Promise<void> => {
  if (frame.kind === 'frame.yield') {
  return new Promise((resolve, reject) => {
- setImmediate(() => {
+ const resume = () => {
  try {
  resumeWithDispatcher(frame, queue, visitor)
  resolve()
  } catch (err) {
  reject(err)
  }
- })
+ }
+ if (SHOULD_YIELD) {
+ setImmediate(resume)
+ } else {
+ resume()
+ }
  })
  }
 

src/visitor.js

@@ -67,6 +67,11 @@ import {
  REACT_LAZY_TYPE
 } from './symbols'
 
+// In the presence of setImmediate, i.e. on Node, we'll enable the
+// yielding behavior that gives the event loop a chance to continue
+// running when the prepasses would otherwise take too long
+export const SHOULD_YIELD = typeof setImmediate === 'function';
+
 // Time in ms after which the otherwise synchronous visitor yields so that
 // the event loop is not interrupted for too long
 const YIELD_AFTER_MS = process.env.NODE_ENV !== 'production' ? 20 : 5
@@ -189,7 +194,7 @@ const visitLoop = (
  restoreContextStore(traversalStore.pop())
  }
 
- if (Date.now() - start > YIELD_AFTER_MS) {
+ if (SHOULD_YIELD && (Date.now() - start > YIELD_AFTER_MS)) {
  return true
  }
  }