JavaScript Language | 30 Minute Test 6

A ”src” attribute could be used to add any external code into the HTML document.

a==b returns a true if a and b refer to the same objec ,so they are equal, else it returns a false.

lvalue is a historical term that means “an expression that can legally appear on the left side of an assignment expression.” In JavaScript, variables, properties of objects, and elements of arrays are lvalues.

None.

The debugger statement normally does nothing. If, however, a debugger program is available and is running, then an implementation may (but is not required to) perform some kind of debugging action. In practice, this statement acts like a breakpoint: execution of JavaScript code stops and you can use the debugger to print variable’s values.

Object serialization is the process of converting an object’s state to a string from which it can later be restored.

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The code above is an invocation expression: it includes a function expression o.m and two argument expressions, x and y.

The state stored in d is 1 because d was not reset.

Dynamic scoping creates variables that can be called from outside the block of code in which they are defined. A variable declared in this fashion is sometimes called a public variable.

When used to define new properties, any attributes you omit default to false. Therefore, both Object.defineProperty() and Object.defineProperties() can be used to create and modify the attributes.

One can refresh the webpage in JavaScript by using location.reload.

One way for a module to avoid the creation of global variables is to use an object as its namespace. Instead of defining global functions and variables, it stores the functions and values as properties of an object (which may be referenced to a global variable).

The split() method can take regular expressions as its arguments. The split() method generally breaks the string on which it is called into an array of substrings, using the argument as a separator.

ADsafe was one of the first security subsets proposed. It was created by Douglas Crockford (who also defined The Good Parts subset).ADsafe relies on static verification only, and it uses JSLint as its verifier. It forbids access to most global variables and defines an ADSAFE variable that provides access to a secure API, including special-purpose DOM methods. ADsafe is not in wide use, but it was an influential proof-of-concept that influenced other secure subsets.

Iterators that work on finite collections throw StopIteration from their next() method when there are no more values to iterate. StopIteration is a property of the global object in JavaScript 1.7. Its value is an ordinary object (with no properties of its own) that is reserved for this special purpose of terminating iterations. Note, in particular,that StopIteration is not a constructor function like TypeError() or RangeError().

Removing attributes and tags is very easy with the standard delete operator :

The write() method never blocks. If Node cannot write the data immediately and has to buffer it internally, the write() method returns false.

Just like the JavaScript classes use new operator to instantiate, so does the Java classes.

Node objects that generate events (known as event emitters) define an on() method for registering handlers.

To retrieve a value, pass the name to getItem().

The default value of the type attribute is “text/javascript”. You can specify this type explicitly if you want, but it is never necessary.

One of the most important properties of the Window object is document: it refers to a Document object that represents the content displayed in the window.

The Document object has important methods such as getElementById(), which returns a single document element (representing an open/close pair of HTML tags and all of the content between them) based on the value of its id attribute.

GWT, the Google Web Toolkit , is a completely different kind of client-side framework. It defines a web application API in Java and provides a compiler to translate your Java programs into compatible clientside JavaScript.

The location property of the Window object refers to a Location object, which represents the current URL of the document displayed in the window, and which also defines methods for making the window load a new document.

The assign() method of the Location object makes the window load and display the document at the URL you specify.

The platform and appVersion can be used for browser sniffing.

The fourth argument to open() is useful only when the second argument names an existing window. This fourth argument is a boolean value that indicates whether the URL specified as the first argument should replace the current entry in the window’s browsing history (true) or create a new entry in the window’s browsing history (false). Omitting this argument is the same as passing false.

The documentElement property of the Document class refers to the root element of the document. This is always an HTML element.