Core: Prevent Object.prototype pollution for $.extend( true, ... )

[jquery.git] / src / core.js

/* global Symbol */
// Defining this global in .eslintrc.json would create a danger of using the global
// unguarded in another place, it seems safer to define global only for this module

define( [
        "./var/arr",
        "./var/document",
        "./var/getProto",
        "./var/slice",
        "./var/concat",
        "./var/push",
        "./var/indexOf",
        "./var/class2type",
        "./var/toString",
        "./var/hasOwn",
        "./var/fnToString",
        "./var/ObjectFunctionString",
        "./var/support",
        "./var/isFunction",
        "./var/isWindow",
        "./core/DOMEval",
        "./core/toType"
], function( arr, document, getProto, slice, concat, push, indexOf,
        class2type, toString, hasOwn, fnToString, ObjectFunctionString,
        support, isFunction, isWindow, DOMEval, toType ) {

"use strict";

var
        version = "@VERSION",

        // Define a local copy of jQuery
        jQuery = function( selector, context ) {

                // The jQuery object is actually just the init constructor 'enhanced'
                // Need init if jQuery is called (just allow error to be thrown if not included)
                return new jQuery.fn.init( selector, context );
        },

        // Support: Android <=4.0 only
        // Make sure we trim BOM and NBSP
        rtrim = /^[\s\uFEFF\xA0]+|[\s\uFEFF\xA0]+$/g;

jQuery.fn = jQuery.prototype = {

        // The current version of jQuery being used
        jquery: version,

        constructor: jQuery,

        // The default length of a jQuery object is 0
        length: 0,

        toArray: function() {
                return slice.call( this );
        },

        // Get the Nth element in the matched element set OR
        // Get the whole matched element set as a clean array
        get: function( num ) {

                // Return all the elements in a clean array
                if ( num == null ) {
                        return slice.call( this );
                }

                // Return just the one element from the set
                return num < 0 ? this[ num + this.length ] : this[ num ];
        },

        // Take an array of elements and push it onto the stack
        // (returning the new matched element set)
        pushStack: function( elems ) {

                // Build a new jQuery matched element set
                var ret = jQuery.merge( this.constructor(), elems );

                // Add the old object onto the stack (as a reference)
                ret.prevObject = this;

                // Return the newly-formed element set
                return ret;
        },

        // Execute a callback for every element in the matched set.
        each: function( callback ) {
                return jQuery.each( this, callback );
        },

        map: function( callback ) {
                return this.pushStack( jQuery.map( this, function( elem, i ) {
                        return callback.call( elem, i, elem );
                } ) );
        },

        slice: function() {
                return this.pushStack( slice.apply( this, arguments ) );
        },

        first: function() {
                return this.eq( 0 );
        },

        last: function() {
                return this.eq( -1 );
        },

        eq: function( i ) {
                var len = this.length,
                        j = +i + ( i < 0 ? len : 0 );
                return this.pushStack( j >= 0 && j < len ? [ this[ j ] ] : [] );
        },

        end: function() {
                return this.prevObject || this.constructor();
        },

        // For internal use only.
        // Behaves like an Array's method, not like a jQuery method.
        push: push,
        sort: arr.sort,
        splice: arr.splice
};

jQuery.extend = jQuery.fn.extend = function() {
        var options, name, src, copy, copyIsArray, clone,
                target = arguments[ 0 ] || {},
                i = 1,
                length = arguments.length,
                deep = false;

        // Handle a deep copy situation
        if ( typeof target === "boolean" ) {
                deep = target;

                // Skip the boolean and the target
                target = arguments[ i ] || {};
                i++;
        }

        // Handle case when target is a string or something (possible in deep copy)
        if ( typeof target !== "object" && !isFunction( target ) ) {
                target = {};
        }

        // Extend jQuery itself if only one argument is passed
        if ( i === length ) {
                target = this;
                i--;
        }

        for ( ; i < length; i++ ) {

                // Only deal with non-null/undefined values
                if ( ( options = arguments[ i ] ) != null ) {

                        // Extend the base object
                        for ( name in options ) {
                                copy = options[ name ];

                                // Prevent Object.prototype pollution
                                // Prevent never-ending loop
                                if ( name === "__proto__" || target === copy ) {
                                        continue;
                                }

                                // Recurse if we're merging plain objects or arrays
                                if ( deep && copy && ( jQuery.isPlainObject( copy ) ||
                                        ( copyIsArray = Array.isArray( copy ) ) ) ) {
                                        src = target[ name ];

                                        // Ensure proper type for the source value
                                        if ( copyIsArray && !Array.isArray( src ) ) {
                                                clone = [];
                                        } else if ( !copyIsArray && !jQuery.isPlainObject( src ) ) {
                                                clone = {};
                                        } else {
                                                clone = src;
                                        }
                                        copyIsArray = false;

                                        // Never move original objects, clone them
                                        target[ name ] = jQuery.extend( deep, clone, copy );

                                // Don't bring in undefined values
                                } else if ( copy !== undefined ) {
                                        target[ name ] = copy;
                                }
                        }
                }
        }

        // Return the modified object
        return target;
};

jQuery.extend( {

        // Unique for each copy of jQuery on the page
        expando: "jQuery" + ( version + Math.random() ).replace( /\D/g, "" ),

        // Assume jQuery is ready without the ready module
        isReady: true,

        error: function( msg ) {
                throw new Error( msg );
        },

        noop: function() {},

        isPlainObject: function( obj ) {
                var proto, Ctor;

                // Detect obvious negatives
                // Use toString instead of jQuery.type to catch host objects
                if ( !obj || toString.call( obj ) !== "[object Object]" ) {
                        return false;
                }

                proto = getProto( obj );

                // Objects with no prototype (e.g., `Object.create( null )`) are plain
                if ( !proto ) {
                        return true;
                }

                // Objects with prototype are plain iff they were constructed by a global Object function
                Ctor = hasOwn.call( proto, "constructor" ) && proto.constructor;
                return typeof Ctor === "function" && fnToString.call( Ctor ) === ObjectFunctionString;
        },

        isEmptyObject: function( obj ) {
                var name;

                for ( name in obj ) {
                        return false;
                }
                return true;
        },

        // Evaluates a script in a global context
        globalEval: function( code, options ) {
                DOMEval( code, { nonce: options && options.nonce } );
        },

        each: function( obj, callback ) {
                var length, i = 0;

                if ( isArrayLike( obj ) ) {
                        length = obj.length;
                        for ( ; i < length; i++ ) {
                                if ( callback.call( obj[ i ], i, obj[ i ] ) === false ) {
                                        break;
                                }
                        }
                } else {
                        for ( i in obj ) {
                                if ( callback.call( obj[ i ], i, obj[ i ] ) === false ) {
                                        break;
                                }
                        }
                }

                return obj;
        },

        // Support: Android <=4.0 only
        trim: function( text ) {
                return text == null ?
                        "" :
                        ( text + "" ).replace( rtrim, "" );
        },

        // results is for internal usage only
        makeArray: function( arr, results ) {
                var ret = results || [];

                if ( arr != null ) {
                        if ( isArrayLike( Object( arr ) ) ) {
                                jQuery.merge( ret,
                                        typeof arr === "string" ?
                                        [ arr ] : arr
                                );
                        } else {
                                push.call( ret, arr );
                        }
                }

                return ret;
        },

        inArray: function( elem, arr, i ) {
                return arr == null ? -1 : indexOf.call( arr, elem, i );
        },

        // Support: Android <=4.0 only, PhantomJS 1 only
        // push.apply(_, arraylike) throws on ancient WebKit
        merge: function( first, second ) {
                var len = +second.length,
                        j = 0,
                        i = first.length;

                for ( ; j < len; j++ ) {
                        first[ i++ ] = second[ j ];
                }

                first.length = i;

                return first;
        },

        grep: function( elems, callback, invert ) {
                var callbackInverse,
                        matches = [],
                        i = 0,
                        length = elems.length,
                        callbackExpect = !invert;

                // Go through the array, only saving the items
                // that pass the validator function
                for ( ; i < length; i++ ) {
                        callbackInverse = !callback( elems[ i ], i );
                        if ( callbackInverse !== callbackExpect ) {
                                matches.push( elems[ i ] );
                        }
                }

                return matches;
        },

        // arg is for internal usage only
        map: function( elems, callback, arg ) {
                var length, value,
                        i = 0,
                        ret = [];

                // Go through the array, translating each of the items to their new values
                if ( isArrayLike( elems ) ) {
                        length = elems.length;
                        for ( ; i < length; i++ ) {
                                value = callback( elems[ i ], i, arg );

                                if ( value != null ) {
                                        ret.push( value );
                                }
                        }

                // Go through every key on the object,
                } else {
                        for ( i in elems ) {
                                value = callback( elems[ i ], i, arg );

                                if ( value != null ) {
                                        ret.push( value );
                                }
                        }
                }

                // Flatten any nested arrays
                return concat.apply( [], ret );
        },

        // A global GUID counter for objects
        guid: 1,

        // jQuery.support is not used in Core but other projects attach their
        // properties to it so it needs to exist.
        support: support
} );

if ( typeof Symbol === "function" ) {
        jQuery.fn[ Symbol.iterator ] = arr[ Symbol.iterator ];
}

// Populate the class2type map
jQuery.each( "Boolean Number String Function Array Date RegExp Object Error Symbol".split( " " ),
function( i, name ) {
        class2type[ "[object " + name + "]" ] = name.toLowerCase();
} );

function isArrayLike( obj ) {

        // Support: real iOS 8.2 only (not reproducible in simulator)
        // `in` check used to prevent JIT error (gh-2145)
        // hasOwn isn't used here due to false negatives
        // regarding Nodelist length in IE
        var length = !!obj && "length" in obj && obj.length,
                type = toType( obj );

        if ( isFunction( obj ) || isWindow( obj ) ) {
                return false;
        }

        return type === "array" || length === 0 ||
                typeof length === "number" && length > 0 && ( length - 1 ) in obj;
}

return jQuery;
} );