Deferred: Rename `getStackHook` to `getErrorHook` (3.x version)

Rename `jQuery.Deferred.getStackHook` to `jQuery.Deferred.getErrorHook`
to indicate passing an error instance is usually a better choice - it
works with source maps while a raw stack generally does not.

In jQuery `3.7.0`, we'll keep both names, marking the old one as
deprecated. In jQuery `4.0.0` we'll just keep the new one. This
change implements the `3.7.0` version; PR gh-5211 implements
the `4.0.0` one.

Fixes gh-5201
Closes gh-5212
Ref gh-5211

4 files changed, 58 insertions, 11 deletions

diff --git a/src/deferred.js b/src/deferred.js
index 439653f58..5e390b7f6 100644
--- a/src/deferred.js
+++ b/src/deferred.js
@@ -194,7 +194,7 @@ jQuery.extend( {
 
 											if ( jQuery.Deferred.exceptionHook ) {
 												jQuery.Deferred.exceptionHook( e,
-													process.stackTrace );
+													process.error );
 											}
 
 											// Support: Promises/A+ section 2.3.3.3.4.1
@@ -222,10 +222,17 @@ jQuery.extend( {
 								process();
 							} else {
 
-								// Call an optional hook to record the stack, in case of exception
+								// Call an optional hook to record the error, in case of exception
 								// since it's otherwise lost when execution goes async
-								if ( jQuery.Deferred.getStackHook ) {
-									process.stackTrace = jQuery.Deferred.getStackHook();
+								if ( jQuery.Deferred.getErrorHook ) {
+									process.error = jQuery.Deferred.getErrorHook();
+
+								// The deprecated alias of the above. While the name suggests
+								// returning the stack, not an error instance, jQuery just passes
+								// it directly to `console.warn` so both will work; an instance
+								// just better cooperates with source maps.
+								} else if ( jQuery.Deferred.getStackHook ) {
+									process.error = jQuery.Deferred.getStackHook();
 								}
 								window.setTimeout( process );
 							}
diff --git a/src/deferred/exceptionHook.js b/src/deferred/exceptionHook.js
index 6dbdc8520..cc2cf9c26 100644
--- a/src/deferred/exceptionHook.js
+++ b/src/deferred/exceptionHook.js
@@ -9,12 +9,16 @@ define( [
 // warn about them ASAP rather than swallowing them by default.
 var rerrorNames = /^(Eval|Internal|Range|Reference|Syntax|Type|URI)Error$/;
 
-jQuery.Deferred.exceptionHook = function( error, stack ) {
+// If `jQuery.Deferred.getErrorHook` is defined, `asyncError` is an error
+// captured before the async barrier to get the original error cause
+// which may otherwise be hidden.
+jQuery.Deferred.exceptionHook = function( error, asyncError ) {
 
 	// Support: IE 8 - 9 only
 	// Console exists when dev tools are open, which can happen at any time
 	if ( window.console && window.console.warn && error && rerrorNames.test( error.name ) ) {
-		window.console.warn( "jQuery.Deferred exception: " + error.message, error.stack, stack );
+		window.console.warn( "jQuery.Deferred exception: " + error.message,
+			error.stack, asyncError );
 	}
 };
 
diff --git a/test/unit/deferred.js b/test/unit/deferred.js
index 184dded95..9a8d4152f 100644
--- a/test/unit/deferred.js
+++ b/test/unit/deferred.js
@@ -628,13 +628,13 @@ QUnit[ window.console ? "test" : "skip" ]( "jQuery.Deferred.exceptionHook with s
 		defer = jQuery.Deferred(),
 		oldWarn = window.console.warn;
 
-	jQuery.Deferred.getStackHook = function() {
+	jQuery.Deferred.getErrorHook = function() {
 
 		// Default exceptionHook assumes the stack is in a form console.warn can log,
-		// but a custom getStackHook+exceptionHook pair could save a raw form and
+		// but a custom getErrorHook+exceptionHook pair could save a raw form and
 		// format it to a string only when an exception actually occurs.
 		// For the unit test we just ensure the plumbing works.
-		return "NO STACK FOR YOU";
+		return "NO ERROR FOR YOU";
 	};
 
 	window.console.warn = function() {
@@ -656,13 +656,13 @@ QUnit[ window.console ? "test" : "skip" ]( "jQuery.Deferred.exceptionHook with s
 		} else {
 			assert.ok( /cough_up_hairball/.test( msg ), "Function mentioned: " + msg );
 		}
-		assert.ok( /NO STACK FOR YOU/.test( msg ), "Stack trace included: " + msg );
+		assert.ok( /NO ERROR FOR YOU/.test( msg ), "Error included: " + msg );
 	};
 	defer.then( function() {
 		jQuery.cough_up_hairball();
 	} ).then( null, function( ) {
 		window.console.warn = oldWarn;
-		delete jQuery.Deferred.getStackHook;
+		delete jQuery.Deferred.getErrorHook;
 		done();
 	} );
 
diff --git a/test/unit/deprecated.js b/test/unit/deprecated.js
index 20bea3d2c..ce03f25d8 100644
--- a/test/unit/deprecated.js
+++ b/test/unit/deprecated.js
@@ -661,4 +661,40 @@ QUnit.test( "trim", function( assert ) {
 	assert.equal( jQuery.trim( "\uFEFF \xA0! | \uFEFF" ), "! |", "leading/trailing should be trimmed" );
 } );
 
+if ( includesModule( "deferred" ) ) {
+	QUnit.test( "jQuery.Deferred.exceptionHook with stack hooks", function( assert ) {
+
+		assert.expect( 2 );
+
+		var done = assert.async(),
+			defer = jQuery.Deferred(),
+			oldWarn = window.console.warn;
+
+		jQuery.Deferred.getStackHook = function() {
+
+			// Default exceptionHook assumes the stack is in a form console.warn can log,
+			// but a custom getStackHook+exceptionHook pair could save a raw form and
+			// format it to a string only when an exception actually occurs.
+			// For the unit test we just ensure the plumbing works.
+			return "NO STACK FOR YOU";
+		};
+
+		window.console.warn = function() {
+			var msg = Array.prototype.join.call( arguments, " " );
+			assert.ok( /cough_up_hairball/.test( msg ), "Function mentioned: " + msg );
+			assert.ok( /NO STACK FOR YOU/.test( msg ), "Stack trace included: " + msg );
+		};
+
+		defer.then( function() {
+			jQuery.cough_up_hairball();
+		} ).then( null, function() {
+			window.console.warn = oldWarn;
+			delete jQuery.Deferred.getStackHook;
+			done();
+		} );
+
+		defer.resolve();
+	} );
+}
+
 }