tailieunhanh - Beginning Ajax with ASP.NET- P5

Beginning Ajax with P5:Thank you for purchasing Beginning Ajax with . We know that you have a lot of options when selecting a programming book and are glad that you have chosen ours. We’re sure you will be pleased with the relevant content and high quality you have come to expect from the Wrox Press line of books. | Chapter 3 These are some more comments. This is useful for a larger set of comments that is written in a paragraph like fashion. Datatypes There are three basic or primitive datatypes in JavaScript string number and boolean types. A boolean type can contain either a true or false value. Number types can contain either an integer or floatingpoint number. var boolVar true var numberVar var stringVar This is a string The number datatype can have special values. These special values are Infinity and NaN. A number variable is given the value of Infinity when its maximum capacity is exceeded. Similarly a number variable is given the value of -Infinity when its minimum value is exceeded. A number variable can also have a value of NaN which stands for Not a Number when the variable is assigned the value of an undefined operation such as dividing zero by zero. Infinity values can be compared and all values that equate to infinity are equal that is any result of an operation that equals infinity is equal to any other operation that results in a value of infinity. Any operation involving a value of infinity causes the entire result to be equal to infinity. Unlike infinity NaN must be explicitly tested for using the isNaN function. Escape Codes Strings can contain special characters such as backspaces tabs and carriage returns by escaping the characters that is by using an escape code to represent the character. Escape codes in strings are prefixed by a backslash. The list of escape codes is given in the following table. Escape Code Character or Value Represented b Backspace r Carriage return n Linefeed or newline t Horizontal tab v Vertical tab f Form feed Double quotation mark Single quotation mark 36 JavaScript and the Document Object Model Escape Code Character or Value Represented Backslash 000 Latin-1 character represented by a three-digit octal value in the range 000-377 for example 056. xHH Latin-1 character represented by a two-digit hexadecimal number in the .