jQuery extend 的简单实例_jquery

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;
target = arguments[1] || {};
// skip the boolean and the target
i = 2;
}

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

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

for ( ; i // Only deal with non-null/undefined values
if ( (options = arguments[ i ]) != null ) {
// Extend the base object
for ( name in options ) {
src = target[ name ];
copy = options[ name ];

// Prevent never-ending loop
if ( target === copy ) {
continue;
}

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

} else {
clone = src && jQuery.isPlainObject(src) ? src : {};
}

// 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;
};