return nan

function Formatfloat (afloat, aprecision) {try {precision = default_precision;if (!isnan (aprecision))if (Math.Abs (aprecision) precision = aprecision;catch (e) {precision = default_precision;}try {Number = parsefloat (afloat+ ');if (isNaN

One or one-dollar operator1, delete operator: Deletes a reference to a previously defined object property or method. For example: var o=new Object; O.name= "Superman"; alert (o.name); Output "Superman" Delete O.name; alert (o.name); Output

1. Use JavaScript 1, elements in HTML defines the following 6 properties:Async: Optional, asynchronous download of external script files.CharSet: optional, by specifying the character set of the code through the SRC attribute, most browsers ignore

The development speed of the front-end technology is obvious to all, JS's ECMA standard is no longer 3 of the world, but no matter how hinting, the basic grammar still has to know the new. Whether you are beginners or many years JS programmer, you

Grammar:1. Case-sensitive!!2. Identifier: variable, function name, property name, parameter.1. The first character must be a letter, _, or $2. Other characters can be letters, _,&, or numbers3. Notes:1. Single-line Comment://2. Multiline Comment:/* *

A. How javascript is added to HTML:1. External method:The is written in a new JavaScript file and then introduced in the HTML file, which is added in the head:2. Inline mode:To include JavaScript script code in the HTML event handler properties3.

The number type should be the most interesting data type in ECMAScript, which uses the IEEE754 format to represent integers and floating point values (floating-point numbers are also known as double-precision values in some languages).    To support

1.js Digital-nan and Infinity1, in JS, there is a special value, called Nan (not a number), indicating that the operation to return a numeric value is not returned, such as 0 divided by 0 operation, in other languages will be reported errors or

Objective:5 Primitive basic data types, also called value types: Undefined, Null, Boolean, number, and string.Compound/reference Data type: Object, which is a collection of properties and methods, is essentially a set of unordered name-value pairs.

Js data types: Number, String, Boolean, Undefined, Null, and Object. The data we create in js must be one of the above types. 1, typeof OperatorJs provides the typeof operator to detect the data type, but the result of the typeof operation is only

1. variables are weak types.It can store any type of values. For example:VaR test = "hi ";Alert (TEST); // output "hi"Test = 55;Alert (TEST); // outputs "55" 2. Original Value and reference value.Variables can be stored in two types of values: the

From: http://blog.csdn.net/kfanning/archive/2010/04/14/5485412.aspx Convert to numbers Ecmascript provides two methods to convert non-numeric values into numbers: parseint () and parsefloat ().Note: Only when these methods are called for the string

Http://www.cnblogs.com/Ninputer/archive/2011/08/18/2145045.html   A number of days ago, the technical master vczh developed a function image rendering program that can draw an image with the equation f (x, y) = 0. The principle is to bring the

Node. js supports multi-user web Terminal Implementation and security solutions, and node. js supports multiple users As a common feature of local IDE, terminal (command line) supports git operations and file operations of projects. For WebIDE,

This chapter contains syntax, data types, flow control statements, and functions.1. SyntaxThe syntax of Ecmascrip is similar to the syntax of C and other C languages such as Java and Perl.2. Case-sensitiveEverything in ECMAScript (variables,

JavaScript basic Data typeThere are 6 kinds of data types in javascript: Null, Undefined, Boolean, String, number, Object. Where object is a complex data type.Basic data type: Null, Undefined, Boolean, String, number.Reference data type: Object,

There are five simple data types (also known as basic data types) in ECMAScript: Undefined, Null, Boolean, number, StringECMAScript also has a complex data type--object,object essentially consists of a set of unordered name-value pairs.ECMAScript

This list of some interesting JS topic (from the name of the 44), I believe there are a lot of these topics on the blog, the purpose of this blog is to consolidate some knowledge points, and readers hope to progress together.1. Map function

From: http://blog.csdn.net/kfanning/archive/2010/04/14/5485412.aspxConvert to DigitalECMAScript provides two ways to convert non-numeric primitive values into numbers, namely parseint () and parsefloat ().Note: These methods are called only for

A summary of the advanced programming of JavaScript JavaScript data type: undefined:undefined ( variable declaration but Undefined for initialization) Null:null (Null object pointer, variable will save object type, can be