Build: ESLint: forbid unused function parameters

This commit requires all function parameters to be used, not just the last one.
In cases where that's not possible as we need to match an external API, there's
an escape hatch of prefixing an unused argument with `_`.

This change makes it easier to catch unused AMD dependencies and unused
parameters in internal functions the API of which we may change at will, among
other things.

Unused AMD dependencies have been removed as part of this commit.

Closes gh-4381

16 files changed, 23 insertions, 34 deletions

diff --git a/src/ajax.js b/src/ajax.js
index 31880032d..c1f7b14d9 100644
--- a/src/ajax.js
+++ b/src/ajax.js
@@ -838,7 +838,7 @@ jQuery.extend( {
 	}
 } );
 
-jQuery.each( [ "get", "post" ], function( i, method ) {
+jQuery.each( [ "get", "post" ], function( _i, method ) {
 	jQuery[ method ] = function( url, data, callback, type ) {
 
 		// Shift arguments if data argument was omitted
diff --git a/src/attributes/attr.js b/src/attributes/attr.js
index cd2b3128b..49d5e2550 100644
--- a/src/attributes/attr.js
+++ b/src/attributes/attr.js
@@ -119,7 +119,7 @@ boolHook = {
 	}
 };
 
-jQuery.each( jQuery.expr.match.bool.source.match( /\w+/g ), function( i, name ) {
+jQuery.each( jQuery.expr.match.bool.source.match( /\w+/g ), function( _i, name ) {
 	var getter = attrHandle[ name ] || jQuery.find.attr;
 
 	attrHandle[ name ] = function( elem, name, isXML ) {
diff --git a/src/core.js b/src/core.js
index 5a5c7469e..f1ef9ef97 100644
--- a/src/core.js
+++ b/src/core.js
@@ -4,7 +4,6 @@
 
 define( [
 	"./var/arr",
-	"./var/document",
 	"./var/getProto",
 	"./var/slice",
 	"./var/concat",
@@ -20,7 +19,7 @@ define( [
 	"./var/isWindow",
 	"./core/DOMEval",
 	"./core/toType"
-], function( arr, document, getProto, slice, concat, push, indexOf,
+], function( arr, getProto, slice, concat, push, indexOf,
 	class2type, toString, hasOwn, fnToString, ObjectFunctionString,
 	trim, support, isWindow, DOMEval, toType ) {
 
@@ -365,7 +364,7 @@ if ( typeof Symbol === "function" ) {
 
 // Populate the class2type map
 jQuery.each( "Boolean Number String Function Array Date RegExp Object Error Symbol".split( " " ),
-function( i, name ) {
+function( _i, name ) {
 	class2type[ "[object " + name + "]" ] = name.toLowerCase();
 } );
 
diff --git a/src/core/access.js b/src/core/access.js
index f600600d5..e088a6557 100644
--- a/src/core/access.js
+++ b/src/core/access.js
@@ -37,7 +37,7 @@ var access = function( elems, fn, key, value, chainable, emptyGet, raw ) {
 			// ...except when executing function values
 			} else {
 				bulk = fn;
-				fn = function( elem, key, value ) {
+				fn = function( elem, _key, value ) {
 					return bulk.call( jQuery( elem ), value );
 				};
 			}
diff --git a/src/core/camelCase.js b/src/core/camelCase.js
index 95de46866..61ed90d05 100644
--- a/src/core/camelCase.js
+++ b/src/core/camelCase.js
@@ -6,7 +6,7 @@ define( [], function() {
 var rdashAlpha = /-([a-z])/g;
 
 // Used by camelCase as callback to replace()
-function fcamelCase( all, letter ) {
+function fcamelCase( _all, letter ) {
 	return letter.toUpperCase();
 }
 
diff --git a/src/css.js b/src/css.js
index 2ae0c0c2c..b3b05e40f 100644
--- a/src/css.js
+++ b/src/css.js
@@ -34,7 +34,7 @@ var
 		fontWeight: "400"
 	};
 
-function setPositiveNumber( elem, value, subtract ) {
+function setPositiveNumber( _elem, value, subtract ) {
 
 	// Any relative (+/-) values have already been
 	// normalized at this point
@@ -311,7 +311,7 @@ jQuery.extend( {
 	}
 } );
 
-jQuery.each( [ "height", "width" ], function( i, dimension ) {
+jQuery.each( [ "height", "width" ], function( _i, dimension ) {
 	jQuery.cssHooks[ dimension ] = {
 		get: function( elem, computed, extra ) {
 			if ( computed ) {
diff --git a/src/css/var/swap.js b/src/css/var/swap.js
index 1a9556bad..69388e5f7 100644
--- a/src/css/var/swap.js
+++ b/src/css/var/swap.js
@@ -3,7 +3,7 @@ define( function() {
 "use strict";
 
 // A method for quickly swapping in/out CSS properties to get correct calculations.
-return function( elem, options, callback, args ) {
+return function( elem, options, callback ) {
 	var ret, name,
 		old = {};
 
@@ -13,7 +13,7 @@ return function( elem, options, callback, args ) {
 		elem.style[ name ] = options[ name ];
 	}
 
-	ret = callback.apply( elem, args || [] );
+	ret = callback.call( elem );
 
 	// Revert the old values
 	for ( name in options ) {
diff --git a/src/deferred.js b/src/deferred.js
index 81a1d0140..771e8381b 100644
--- a/src/deferred.js
+++ b/src/deferred.js
@@ -75,7 +75,7 @@ jQuery.extend( {
 					var fns = arguments;
 
 					return jQuery.Deferred( function( newDefer ) {
-						jQuery.each( tuples, function( i, tuple ) {
+						jQuery.each( tuples, function( _i, tuple ) {
 
 							// Map tuples (progress, done, fail) to arguments (done, fail, progress)
 							var fn = typeof fns[ tuple[ 4 ] ] === "function" &&
diff --git a/src/deprecated.js b/src/deprecated.js
index 10d708ce2..4edefaca0 100644
--- a/src/deprecated.js
+++ b/src/deprecated.js
@@ -1,13 +1,9 @@
 define( [
 	"./core",
-	"./core/nodeName",
-	"./core/toType",
-	"./css/cssCamelCase",
-	"./var/isWindow",
 	"./var/slice",
 
 	"./event/alias"
-], function( jQuery, nodeName, toType, cssCamelCase, isWindow, slice ) {
+], function( jQuery, slice ) {
 
 "use strict";
 
diff --git a/src/effects.js b/src/effects.js
index a65283e28..46ad988ad 100644
--- a/src/effects.js
+++ b/src/effects.js
@@ -5,7 +5,6 @@ define( [
 	"./var/rnothtmlwhite",
 	"./css/var/cssExpand",
 	"./css/var/isHiddenWithinTree",
-	"./css/var/swap",
 	"./css/adjustCSS",
 	"./css/cssCamelCase",
 	"./data/var/dataPriv",
@@ -19,7 +18,7 @@ define( [
 	"./css",
 	"./effects/Tween"
 ], function( jQuery, document, rcssNum, rnothtmlwhite, cssExpand,
-	isHiddenWithinTree, swap, adjustCSS, cssCamelCase, dataPriv, showHide ) {
+	isHiddenWithinTree, adjustCSS, cssCamelCase, dataPriv, showHide ) {
 
 "use strict";
 
@@ -621,7 +620,7 @@ jQuery.fn.extend( {
 	}
 } );
 
-jQuery.each( [ "toggle", "show", "hide" ], function( i, name ) {
+jQuery.each( [ "toggle", "show", "hide" ], function( _i, name ) {
 	var cssFn = jQuery.fn[ name ];
 	jQuery.fn[ name ] = function( speed, easing, callback ) {
 		return speed == null || typeof speed === "boolean" ?
diff --git a/src/event/ajax.js b/src/event/ajax.js
index 500b36cdd..dd9c0ffe2 100644
--- a/src/event/ajax.js
+++ b/src/event/ajax.js
@@ -13,7 +13,7 @@ jQuery.each( [
 	"ajaxError",
 	"ajaxSuccess",
 	"ajaxSend"
-], function( i, type ) {
+], function( _i, type ) {
 	jQuery.fn[ type ] = function( fn ) {
 		return this.on( type, fn );
 	};
diff --git a/src/event/alias.js b/src/event/alias.js
index 863c94ad2..46bd1ae80 100644
--- a/src/event/alias.js
+++ b/src/event/alias.js
@@ -10,7 +10,7 @@ define( [
 jQuery.each( ( "blur focus focusin focusout resize scroll click dblclick " +
 	"mousedown mouseup mousemove mouseover mouseout mouseenter mouseleave " +
 	"change select submit keydown keypress keyup contextmenu" ).split( " " ),
-	function( i, name ) {
+	function( _i, name ) {
 
 	// Handle event binding
 	jQuery.fn[ name ] = function( data, fn ) {
diff --git a/src/manipulation.js b/src/manipulation.js
index cca3947ce..4d20ec8d6 100644
--- a/src/manipulation.js
+++ b/src/manipulation.js
@@ -4,7 +4,6 @@ define( [
 	"./var/concat",
 	"./var/isIE",
 	"./var/push",
-	"./var/rcheckableType",
 	"./core/access",
 	"./manipulation/var/rtagName",
 	"./manipulation/var/rscriptType",
@@ -23,9 +22,8 @@ define( [
 	"./traversing",
 	"./selector",
 	"./event"
-], function( jQuery, isAttached, concat, isIE, push,
-	rcheckableType, access, rtagName, rscriptType,
-	wrapMap, getAll, setGlobalEval, buildFragment,
+], function( jQuery, isAttached, concat, isIE, push, access, rtagName,
+	rscriptType, wrapMap, getAll, setGlobalEval, buildFragment,
 	dataPriv, dataUser, acceptData, DOMEval, nodeName ) {
 
 "use strict";
diff --git a/src/offset.js b/src/offset.js
index 531b75ff2..91c96d877 100644
--- a/src/offset.js
+++ b/src/offset.js
@@ -1,15 +1,12 @@
 define( [
 	"./core",
 	"./core/access",
-	"./var/document",
 	"./var/documentElement",
-	"./css/var/rnumnonpx",
-	"./css/curCSS",
 	"./var/isWindow",
 	"./core/init",
 	"./css",
 	"./selector" // contains
-], function( jQuery, access, document, documentElement, rnumnonpx, curCSS, isWindow ) {
+], function( jQuery, access, documentElement, isWindow ) {
 
 "use strict";
 
diff --git a/src/serialize.js b/src/serialize.js
index 0cf5ddb44..6743b78e9 100644
--- a/src/serialize.js
+++ b/src/serialize.js
@@ -113,7 +113,7 @@ jQuery.fn.extend( {
 				rsubmittable.test( this.nodeName ) && !rsubmitterTypes.test( type ) &&
 				( this.checked || !rcheckableType.test( type ) );
 		} )
-		.map( function( i, elem ) {
+		.map( function( _i, elem ) {
 			var val = jQuery( this ).val();
 
 			if ( val == null ) {
diff --git a/src/traversing.js b/src/traversing.js
index 72530ed85..59fa977c2 100644
--- a/src/traversing.js
+++ b/src/traversing.js
@@ -118,7 +118,7 @@ jQuery.each( {
 	parents: function( elem ) {
 		return dir( elem, "parentNode" );
 	},
-	parentsUntil: function( elem, i, until ) {
+	parentsUntil: function( elem, _i, until ) {
 		return dir( elem, "parentNode", until );
 	},
 	next: function( elem ) {
@@ -133,10 +133,10 @@ jQuery.each( {
 	prevAll: function( elem ) {
 		return dir( elem, "previousSibling" );
 	},
-	nextUntil: function( elem, i, until ) {
+	nextUntil: function( elem, _i, until ) {
 		return dir( elem, "nextSibling", until );
 	},
-	prevUntil: function( elem, i, until ) {
+	prevUntil: function( elem, _i, until ) {
 		return dir( elem, "previousSibling", until );
 	},
 	siblings: function( elem ) {