Add Microtasks (#19860)

* Add Microtasks

* Add Microtasks

changelog.md

@@ -50,7 +50,7 @@ becomes an alias for `addr`.
 - Removed deprecated `std/dom_extensions`.
 - Removed deprecated `std/posix.CMSG_SPACE` and `std/posix.CMSG_LEN` that takes wrong argument types.
 - Remove deprecated `osproc.poDemon`, symbol with typo.
-
+- Added [`queueMicrotask`](https://developer.mozilla.org/en-US/docs/Web/API/queueMicrotask) for JavaScript targets.
 - Deprecated `selfExe` for Nimscript.
 
 

lib/js/jscore.nim

@@ -132,3 +132,8 @@ since (1, 7):
       var arrai = @[1, 2, 3]
       assert arrai.shift() == 1
       assert arrai == @[2, 3]
+
+  func queueMicrotask*(function: proc) {.importjs: "$1(#)".} =
+    ## * https://developer.mozilla.org/en-US/docs/Web/API/queueMicrotask
+    ## * https://developer.mozilla.org/en-US/docs/Web/API/HTML_DOM_API/Microtask_guide
+    runnableExamples: queueMicrotask(proc() = echo "Microtask")