Leverage coalescing operators. NFC

Note that this bumps minimum Chrome & Firefox versions, as well as JS version from ES2020 to ES2021.

I believe this is not blocked on #11984 as it doesn't require Closure to emit runtime helpers.

This is mostly automated with ast-grep, bunch of custom rules, and a few manual fixups. Best viewed with "ignore whitespace changes" (https://github.com/emscripten-core/emscripten/pull/20531/files) due to indentation changes and due to first commit being #20530.

Care was taken to ensure that false-y conditions still use `||` where it might matter and only null-ish conditions use `??`.

Author: RReverser

src/Fetch.js

@@ -84,7 +84,7 @@ function fetchDeleteCachedData(db, fetch, onsuccess, onerror) {
 
   var fetch_attr = fetch + {{{ C_STRUCTS.emscripten_fetch_t.__attributes }}};
   var path = HEAPU32[fetch_attr + {{{ C_STRUCTS.emscripten_fetch_attr_t.destinationPath }}} >> 2];
-  if (!path) path = HEAPU32[fetch + {{{ C_STRUCTS.emscripten_fetch_t.url }}} >> 2];
+  path ||= HEAPU32[fetch + {{{ C_STRUCTS.emscripten_fetch_t.url }}} >> 2];
   var pathStr = UTF8ToString(path);
 
   try {
@@ -133,7 +133,7 @@ function fetchLoadCachedData(db, fetch, onsuccess, onerror) {
 
   var fetch_attr = fetch + {{{ C_STRUCTS.emscripten_fetch_t.__attributes }}};
   var path = HEAPU32[fetch_attr + {{{ C_STRUCTS.emscripten_fetch_attr_t.destinationPath }}} >> 2];
-  if (!path) path = HEAPU32[fetch + {{{ C_STRUCTS.emscripten_fetch_t.url }}} >> 2];
+  path ||= HEAPU32[fetch + {{{ C_STRUCTS.emscripten_fetch_t.url }}} >> 2];
   var pathStr = UTF8ToString(path);
 
   try {
@@ -198,7 +198,7 @@ function fetchCacheData(/** @type {IDBDatabase} */ db, fetch, data, onsuccess, o
 
   var fetch_attr = fetch + {{{ C_STRUCTS.emscripten_fetch_t.__attributes }}};
   var destinationPath = HEAPU32[fetch_attr + {{{ C_STRUCTS.emscripten_fetch_attr_t.destinationPath }}} >> 2];
-  if (!destinationPath) destinationPath = HEAPU32[fetch + {{{ C_STRUCTS.emscripten_fetch_t.url }}} >> 2];
+  destinationPath ||= HEAPU32[fetch + {{{ C_STRUCTS.emscripten_fetch_t.url }}} >> 2];
   var destinationPathStr = UTF8ToString(destinationPath);
 
   try {
@@ -248,7 +248,7 @@ function fetchXHR(fetch, onsuccess, onerror, onprogress, onreadystatechange) {
 
   var fetch_attr = fetch + {{{ C_STRUCTS.emscripten_fetch_t.__attributes }}};
   var requestMethod = UTF8ToString(fetch_attr + {{{ C_STRUCTS.emscripten_fetch_attr_t.requestMethod }}});
-  if (!requestMethod) requestMethod = 'GET';
+  requestMethod ||= 'GET';
   var timeoutMsecs = {{{ makeGetValue('fetch_attr', C_STRUCTS.emscripten_fetch_attr_t.timeoutMSecs, 'u32') }}};
   var userName = {{{ makeGetValue('fetch_attr', C_STRUCTS.emscripten_fetch_attr_t.userName, '*') }}};
   var password = {{{ makeGetValue('fetch_attr', C_STRUCTS.emscripten_fetch_attr_t.password, '*') }}};
@@ -354,12 +354,12 @@ function fetchXHR(fetch, onsuccess, onerror, onprogress, onreadystatechange) {
 #if FETCH_DEBUG
       dbg(`fetch: xhr of URL "${xhr.url_}" / responseURL "${xhr.responseURL}" succeeded with status ${xhr.status}`);
 #endif
-      if (onsuccess) onsuccess(fetch, xhr, e);
+      onsuccess?.(fetch, xhr, e);
     } else {
 #if FETCH_DEBUG
       dbg(`fetch: xhr of URL "${xhr.url_}" / responseURL "${xhr.responseURL}" failed with status ${xhr.status}`);
 #endif
-      if (onerror) onerror(fetch, xhr, e);
+      onerror?.(fetch, xhr, e);
     }
   };
   xhr.onerror = (e) => {
@@ -371,7 +371,7 @@ function fetchXHR(fetch, onsuccess, onerror, onprogress, onreadystatechange) {
     dbg(`fetch: xhr of URL "${xhr.url_}" / responseURL "${xhr.responseURL}" finished with error, readyState ${xhr.readyState} and status ${xhr.status}`);
 #endif
     saveResponseAndStatus();
-    if (onerror) onerror(fetch, xhr, e);
+    onerror?.(fetch, xhr, e);
   };
   xhr.ontimeout = (e) => {
     // check if xhr was aborted by user and don't try to call back
@@ -381,7 +381,7 @@ function fetchXHR(fetch, onsuccess, onerror, onprogress, onreadystatechange) {
 #if FETCH_DEBUG
     dbg(`fetch: xhr of URL "${xhr.url_}" / responseURL "${xhr.responseURL}" timed out, readyState ${xhr.readyState} and status ${xhr.status}`);
 #endif
-    if (onerror) onerror(fetch, xhr, e);
+    onerror?.(fetch, xhr, e);
   };
   xhr.onprogress = (e) => {
     // check if xhr was aborted by user and don't try to call back
@@ -410,7 +410,7 @@ function fetchXHR(fetch, onsuccess, onerror, onprogress, onreadystatechange) {
     if (xhr.readyState >= 3 && xhr.status === 0 && e.loaded > 0) xhr.status = 200;
     HEAPU16[fetch + {{{ C_STRUCTS.emscripten_fetch_t.status }}} >> 1] = xhr.status;
     if (xhr.statusText) stringToUTF8(xhr.statusText, fetch + {{{ C_STRUCTS.emscripten_fetch_t.statusText }}}, 64);
-    if (onprogress) onprogress(fetch, xhr, e);
+    onprogress?.(fetch, xhr, e);
     if (ptr) {
       _free(ptr);
     }
@@ -425,7 +425,7 @@ function fetchXHR(fetch, onsuccess, onerror, onprogress, onreadystatechange) {
     if (xhr.readyState >= 2) {
       HEAPU16[fetch + {{{ C_STRUCTS.emscripten_fetch_t.status }}} >> 1] = xhr.status;
     }
-    if (onreadystatechange) onreadystatechange(fetch, xhr, e);
+    onreadystatechange?.(fetch, xhr, e);
   };
 #if FETCH_DEBUG
   dbg(`fetch: xhr.send(data=${data})`);
@@ -436,7 +436,7 @@ function fetchXHR(fetch, onsuccess, onerror, onprogress, onreadystatechange) {
 #if FETCH_DEBUG
     dbg(`fetch: xhr failed with exception: ${e}`);
 #endif
-    if (onerror) onerror(fetch, xhr, e);
+    onerror?.(fetch, xhr, e);
   }
 }
 
@@ -468,14 +468,14 @@ function startFetch(fetch, successcb, errorcb, progresscb, readystatechangecb) {
     {{{ runtimeKeepalivePop() }}}
     doCallback(() => {
       if (onsuccess) {{{ makeDynCall('vp', 'onsuccess') }}}(fetch);
-      else if (successcb) successcb(fetch);
+      else successcb?.(fetch);
     });
   };
 
   var reportProgress = (fetch, xhr, e) => {
     doCallback(() => {
       if (onprogress) {{{ makeDynCall('vp', 'onprogress') }}}(fetch);
-      else if (progresscb) progresscb(fetch);
+      else progresscb?.(fetch);
     });
   };
 
@@ -486,7 +486,7 @@ function startFetch(fetch, successcb, errorcb, progresscb, readystatechangecb) {
     {{{ runtimeKeepalivePop() }}}
     doCallback(() => {
       if (onerror) {{{ makeDynCall('vp', 'onerror') }}}(fetch);
-      else if (errorcb) errorcb(fetch);
+      else errorcb?.(fetch);
     });
   };
 
@@ -496,7 +496,7 @@ function startFetch(fetch, successcb, errorcb, progresscb, readystatechangecb) {
 #endif
     doCallback(() => {
       if (onreadystatechange) {{{ makeDynCall('vp', 'onreadystatechange') }}}(fetch);
-      else if (readystatechangecb) readystatechangecb(fetch);
+      else readystatechangecb?.(fetch);
     });
   };
 
@@ -519,7 +519,7 @@ function startFetch(fetch, successcb, errorcb, progresscb, readystatechangecb) {
       {{{ runtimeKeepalivePop() }}}
       doCallback(() => {
         if (onsuccess) {{{ makeDynCall('vp', 'onsuccess') }}}(fetch);
-        else if (successcb) successcb(fetch);
+        else successcb?.(fetch);
       });
     };
     var storeError = (fetch, xhr, e) => {
@@ -529,7 +529,7 @@ function startFetch(fetch, successcb, errorcb, progresscb, readystatechangecb) {
       {{{ runtimeKeepalivePop() }}}
       doCallback(() => {
         if (onsuccess) {{{ makeDynCall('vp', 'onsuccess') }}}(fetch);
-        else if (successcb) successcb(fetch);
+        else successcb?.(fetch);
       });
     };
     fetchCacheData(Fetch.dbInstance, fetch, xhr.response, storeSuccess, storeError);

src/cpuprofiler.js

@@ -148,37 +148,35 @@ var emscriptenCpuProfiler = {
   createSection: function createSection(number, name, drawColor, traceable) {
     while (this.sections.length <= number) this.sections.push(null); // Keep an array structure.
     var sect = this.sections[number];
-    if (!sect) {
-      sect = {
-        count: 0,
-        name,
-        startTick: 0,
-        accumulatedTimeInsideMainLoop: 0,
-        accumulatedTimeOutsideMainLoop: 0,
-        frametimesInsideMainLoop: [],
-        frametimesOutsideMainLoop: [],
-        drawColor,
-        traceable,
-        accumulatedFrameTimeInsideMainLoop: function(startX, numSamples) {
-          var total = 0;
-          numSamples = Math.min(numSamples, this.frametimesInsideMainLoop.length);
-          for (var i = 0; i < numSamples; ++i) {
-            var x = (startX + i) % this.frametimesInsideMainLoop.length;
-            if (this.frametimesInsideMainLoop[x]) total += this.frametimesInsideMainLoop[x];
-          }
-          return total;
-        },
-        accumulatedFrameTimeOutsideMainLoop: function(startX, numSamples) {
-          var total = 0;
-          numSamples = Math.min(numSamples, this.frametimesInsideMainLoop.length);
-          for (var i = 0; i < numSamples; ++i) {
-            var x = (startX + i) % this.frametimesInsideMainLoop.length;
-            if (this.frametimesOutsideMainLoop[x]) total += this.frametimesOutsideMainLoop[x];
-          }
-          return total;
+    sect ||= {
+      count: 0,
+      name,
+      startTick: 0,
+      accumulatedTimeInsideMainLoop: 0,
+      accumulatedTimeOutsideMainLoop: 0,
+      frametimesInsideMainLoop: [],
+      frametimesOutsideMainLoop: [],
+      drawColor,
+      traceable,
+      accumulatedFrameTimeInsideMainLoop: function(startX, numSamples) {
+        var total = 0;
+        numSamples = Math.min(numSamples, this.frametimesInsideMainLoop.length);
+        for (var i = 0; i < numSamples; ++i) {
+          var x = (startX + i) % this.frametimesInsideMainLoop.length;
+          if (this.frametimesInsideMainLoop[x]) total += this.frametimesInsideMainLoop[x];
         }
-      };
-    }
+        return total;
+      },
+      accumulatedFrameTimeOutsideMainLoop: function(startX, numSamples) {
+        var total = 0;
+        numSamples = Math.min(numSamples, this.frametimesInsideMainLoop.length);
+        for (var i = 0; i < numSamples; ++i) {
+          var x = (startX + i) % this.frametimesInsideMainLoop.length;
+          if (this.frametimesOutsideMainLoop[x]) total += this.frametimesOutsideMainLoop[x];
+        }
+        return total;
+      }
+    };
     sect.name = name;
     this.sections[number] = sect;
   },
@@ -368,7 +366,7 @@ var emscriptenCpuProfiler = {
       fpsOverlay.style = 'position: fixed; font-weight: bold; padding: 3px; -webkit-touch-callout: none; -webkit-user-select: none; -khtml-user-select: none; -moz-user-select: none; -ms-user-select: none; user-select: none; cursor: pointer;';
       fpsOverlay.onclick = () => {
         var view = document.getElementById('cpuprofiler_canvas');
-        if (view) view.scrollIntoView();
+        view?.scrollIntoView();
       };
       fpsOverlay.oncontextmenu = (e) => e.preventDefault();
       document.body.appendChild(fpsOverlay);
@@ -532,14 +530,14 @@ var emscriptenCpuProfiler = {
   },
 
   detectWebGLContext: function() {
-    if (Module['canvas'] && Module['canvas'].GLctxObject && Module['canvas'].GLctxObject.GLctx) return Module['canvas'].GLctxObject.GLctx;
+    if (Module['canvas']?.GLctxObject?.GLctx) return Module['canvas'].GLctxObject.GLctx;
     else if (typeof GLctx != 'undefined') return GLctx;
     else if (Module.ctx) return Module.ctx;
     return null;
   },
 
   toggleHookWebGL: function(glCtx) {
-    if (!glCtx) glCtx = this.detectWebGLContext();
+    glCtx ||= this.detectWebGLContext();
     if (this.hookedWebGLContexts.includes(glCtx)) this.unhookWebGL(glCtx);
     else this.hookWebGL(glCtx);
   },
@@ -563,7 +561,7 @@ var emscriptenCpuProfiler = {
   },
 
   unhookWebGL: function(glCtx) {
-    if (!glCtx) glCtx = this.detectWebGLContext();
+    glCtx ||= this.detectWebGLContext();
     if (!glCtx.cpuprofilerAlreadyHooked) return;
     glCtx.cpuprofilerAlreadyHooked = false;
     this.hookedWebGLContexts.splice(this.hookedWebGLContexts.indexOf(glCtx), 1);
@@ -601,7 +599,7 @@ var emscriptenCpuProfiler = {
   },
 
   hookWebGL: function(glCtx) {
-    if (!glCtx) glCtx = this.detectWebGLContext();
+    glCtx ||= this.detectWebGLContext();
     if (!glCtx) return;
     if (!((typeof WebGLRenderingContext != 'undefined' && glCtx instanceof WebGLRenderingContext)
      || (typeof WebGL2RenderingContext != 'undefined' && glCtx instanceof WebGL2RenderingContext))) {

src/embind/embind.js

@@ -1371,9 +1371,7 @@ var LibraryEmbind = {
         return ptr;
       },
       destructor(ptr) {
-        if (this.rawDestructor) {
-          this.rawDestructor(ptr);
-        }
+        this.rawDestructor?.(ptr);
       },
       'argPackAdvance': GenericWireTypeSize,
       'readValueFromPointer': readPointer,
@@ -1807,12 +1805,8 @@ var LibraryEmbind = {
                            rawDestructor) => {
     name = readLatin1String(name);
     getActualType = embind__requireFunction(getActualTypeSignature, getActualType);
-    if (upcast) {
-      upcast = embind__requireFunction(upcastSignature, upcast);
-    }
-    if (downcast) {
-      downcast = embind__requireFunction(downcastSignature, downcast);
-    }
+    upcast &&= embind__requireFunction(upcastSignature, upcast);
+    downcast &&= embind__requireFunction(downcastSignature, downcast);
     rawDestructor = embind__requireFunction(destructorSignature, rawDestructor);
     var legalFunctionName = makeLegalFunctionName(name);
 
@@ -1867,9 +1861,7 @@ var LibraryEmbind = {
 
         if (registeredClass.baseClass) {
           // Keep track of class hierarchy. Used to allow sub-classes to inherit class functions.
-          if (registeredClass.baseClass.__derivedClasses === undefined) {
-            registeredClass.baseClass.__derivedClasses = [];
-          }
+          registeredClass.baseClass.__derivedClasses ??= [];
 
           registeredClass.baseClass.__derivedClasses.push(registeredClass);
         }

src/embind/emval.js

@@ -336,9 +336,7 @@ var LibraryEmVal = {
       }
       var rv = kind === /* CONSTRUCTOR */ 1 ? reflectConstruct(func, argN) : func.apply(obj, argN);
       for (var i = 0; i < argCount; ++i) {
-        if (types[i].deleteObject) {
-          types[i].deleteObject(argN[i]);
-        }
+        types[i].deleteObject?.(argN[i]);
       }
       return emval_returnValue(retType, destructorsRef, rv);
     };

src/headless.js

@@ -83,9 +83,7 @@ var window = {
   eventListeners: {},
   addEventListener(id, func) {
     var listeners = this.eventListeners[id];
-    if (!listeners) {
-      listeners = this.eventListeners[id] = [];
-    }
+    listeners ||= this.eventListeners[id] = [];
     listeners.push(func);
   },
   removeEventListener(id, func) {
@@ -100,9 +98,7 @@ var window = {
   },
   callEventListeners(id) {
     var listeners = this.eventListeners[id];
-    if (listeners) {
-      listeners.forEach((listener) => listener());
-    }
+    listeners?.forEach((listener) => listener());
   },
   URL: {
     createObjectURL(x) {
@@ -161,17 +157,15 @@ var document = {
   },
   elements: {},
   querySelector(id) {
-    if (!document.elements[id]) {
-      document.elements[id] = {
-        classList: {
-          add() {},
-          remove() {},
-        },
-        eventListeners: {},
-        addEventListener: document.addEventListener,
-        removeEventListener: document.removeEventListener,
-        callEventListeners: document.callEventListeners,
-      };
+    document.elements[id] ||= {
+      classList: {
+        add() {},
+        remove() {},
+      },
+      eventListeners: {},
+      addEventListener: document.addEventListener,
+      removeEventListener: document.removeEventListener,
+      callEventListeners: document.callEventListeners,
     };
     return document.elements[id];
   },
@@ -214,7 +208,7 @@ var XMLHttpRequest = function() {
       } else {
         window.setTimeout(() => {
           this.doSend();
-          if (this.onload) this.onload();
+          this.onload?.();
         }, 0);
       }
     },
@@ -239,7 +233,7 @@ var Image = () => {
     this.complete = true;
     this.width = 64;
     this.height = 64;
-    if (this.onload) this.onload();
+    this.onload?.();
   });
 };
 var Worker = (workerPath) => {
@@ -252,7 +246,7 @@ var Worker = (workerPath) => {
 
   function duplicateJSON(json) {
     function handleTypedArrays(key, value) {
-      if (value && value.toString && value.toString().substring(0, 8) == '[object ' && value.length && value.byteLength) {
+      if (value?.toString && value.toString().substring(0, 8) == '[object ' && value.length && value.byteLength) {
         return Array.prototype.slice.call(value);
       }
       return value;
@@ -293,6 +287,4 @@ if (typeof console == 'undefined') {
 }
 
 // additional setup
-if (!Module['canvas']) {
-  Module['canvas'] = document.getElementById('canvas');
-}
+Module['canvas'] ||= document.getElementById('canvas');