Core: Standardize indexOf comparisons

not present: `< 0`
present: `> -1`
at index: `=== N`

(cherry picked from commit 53aa87f3bf4284763405f3eb8affff296e55ba4f)

Closes gh-1985

src/ajax/jsonp.js

@@ -25,7 +25,8 @@ jQuery.ajaxPrefilter( "json jsonp", function( s, originalSettings, jqXHR ) {
 		jsonProp = s.jsonp !== false && ( rjsonp.test( s.url ) ?
 			"url" :
 			typeof s.data === "string" &&
-				!( s.contentType || "" ).indexOf("application/x-www-form-urlencoded") &&
+				( s.contentType || "" )
+					.indexOf("application/x-www-form-urlencoded") === 0 &&
 				rjsonp.test( s.data ) && "data"
 		);
 

src/ajax/load.js

@@ -24,7 +24,7 @@ jQuery.fn.load = function( url, params, callback ) {
 		self = this,
 		off = url.indexOf(" ");
 
-	if ( off >= 0 ) {
+	if ( off > -1 ) {
 		selector = jQuery.trim( url.slice( off, url.length ) );
 		url = url.slice( 0, off );
 	}

src/attributes/classes.js

@@ -76,7 +76,7 @@ jQuery.fn.extend({
 					j = 0;
 					while ( (clazz = classes[j++]) ) {
 						// Remove *all* instances
-						while ( cur.indexOf( " " + clazz + " " ) >= 0 ) {
+						while ( cur.indexOf( " " + clazz + " " ) > -1 ) {
 							cur = cur.replace( " " + clazz + " ", " " );
 						}
 					}
@@ -149,7 +149,7 @@ jQuery.fn.extend({
 			l = this.length;
 		for ( ; i < l; i++ ) {
 			if ( this[i].nodeType === 1 &&
-				(" " + this[i].className + " ").replace(rclass, " ").indexOf( className ) >= 0 ) {
+				(" " + this[i].className + " ").replace(rclass, " ").indexOf( className ) > -1 ) {
 
 				return true;
 			}

src/attributes/val.js

@@ -128,7 +128,7 @@ jQuery.extend({
 				while ( i-- ) {
 					option = options[ i ];
 					if ( (option.selected =
-							jQuery.inArray( jQuery.valHooks.option.get( option ), values ) >= 0) ) {
+							jQuery.inArray( jQuery.valHooks.option.get( option ), values ) > -1) ) {
 						optionSet = true;
 					}
 				}
@@ -149,7 +149,7 @@ jQuery.each([ "radio", "checkbox" ], function() {
 	jQuery.valHooks[ this ] = {
 		set: function( elem, value ) {
 			if ( jQuery.isArray( value ) ) {
-				return ( elem.checked = jQuery.inArray( jQuery(elem).val(), value ) >= 0 );
+				return ( elem.checked = jQuery.inArray( jQuery(elem).val(), value ) > -1 );
 			}
 		}
 	};

src/event.js

@@ -250,7 +250,7 @@ jQuery.event = {
 			return;
 		}
 
-		if ( type.indexOf(".") >= 0 ) {
+		if ( type.indexOf(".") > -1 ) {
 			// Namespaced trigger; create a regexp to match event type in handle()
 			namespaces = type.split(".");
 			type = namespaces.shift();
@@ -460,7 +460,7 @@ jQuery.event = {
 
 						if ( matches[ sel ] === undefined ) {
 							matches[ sel ] = handleObj.needsContext ?
-								jQuery( sel, this ).index( cur ) >= 0 :
+								jQuery( sel, this ).index( cur ) > -1 :
 								jQuery.find( sel, this, null, [ cur ] ).length;
 						}
 						if ( matches[ sel ] ) {

src/manipulation.js

@@ -332,7 +332,7 @@ jQuery.extend({
 
 			// #4087 - If origin and destination elements are the same, and this is
 			// that element, do not do anything
-			if ( selection && jQuery.inArray( elem, selection ) !== -1 ) {
+			if ( selection && jQuery.inArray( elem, selection ) > -1 ) {
 				continue;
 			}
 

src/traversing/findFilter.js

@@ -33,7 +33,7 @@ function winnow( elements, qualifier, not ) {
 	}
 
 	return jQuery.grep( elements, function( elem ) {
-		return ( jQuery.inArray( elem, qualifier ) >= 0 ) !== not;
+		return ( jQuery.inArray( elem, qualifier ) > -1 ) !== not;
 	});
 }