Explain JavaScript scopes and variable declarations promote "translation"

Do you know the value of alert following JavaScript execution? var foo = 1; function Bar () { if (!foo) { var foo =; alert (foo); } Bar (); If you're surprised by the result of "10," you might want to take a good look at this article: var a =

JavaScript Modular Development Explanation and example tutorial

Use require to load jslite, Zepto, and jquery methods, which are the same type of libraries so they are loaded, and here is an instance.Requirejs Reference instance methodThe goal of Requirejs is to encourage the modularity of code, which uses a

If else in JavaScript differs from switch usage

In fact, the meaning of "if else" is the same as the literal meaning, that is, "if" or "otherwise". Let's take a look at an example that uses if. If you're writing a program for a robot, the robot's function is to evaluate the user's hobby. Robot:

JavaScript transforms XML DOM and XML strings into each other

A method that parses an XML string into an XML DOM object. The code is as follows Copy Code function Parsexml (XML) {var xmldom = null;if (typeof domparser!= "undefined") {XMLDOM = (new Domparser ()). parsefromstring

JavaScript arrays and JSON data in objects

For example, the following user object: The code is as follows Copy Code function user (n, a){THIS.name = n;This.age = A;this.tostring = function () {Return "Name:" + THIS.name + ", Age:" + this.age;}}var u = new User

JavaScript determines browser and version based on UserAgent string

The judgment of mobile language version Use Navigator.browserlanguage to get the Windows Phone language version, of course, the hateful Small mobile language version also has compatibility differences, compatible with Mozilla, and AppleWebKit

A search and replace instance of a JavaScript string

The Replace (Regexp,replacement) method has two parameters, the first parameter can be a plain text string or a RegExp object, see the use of RegExp objects, and the second argument is a string or a function. Here are some examples of JS string

JavaScript cannot read script tag src file contents

Usually when we create a script tag on our page, either SRC introduces the external JS file: ? 1 Either write the content directly in the label: ? 1 2 3 The script tag has an

JavaScript Form Validation Common code

JavaScript can be used to validate these input data in an HTML form before the data is sent to the server. The typical form data that is validated by JavaScript is: • Has the user filled out the required items in the form?• Is the email address

JavaScript Associative Array Usage summary

This article summarizes the usage summary of JavaScript associative array, and the friend who has to understand the JS associative array can refer to this article. Just learn JS when it seems to remember that there is no associative array js, write

The scope of variables in JavaScript is described in detail

The following variables have global scope: 1. All definitions in the outermost variable (non-function body part) have global scope. 2. A variable that does not define a direct assignment is declared as a global scope. 3. Properties of all window

JavaScript Regular expression RegExp, matching string, regular specified character

EXEC () retrieves the specified value in the string, returns a value that is found, and returns null if no match is found: The main regexp pattern matching method is exec (), similar to the match method for the string object described in the

JavaScript traversal XML Various methods summary

Traversing the node treeYou often need to loop through XML documents, such as when you need to extract the value of each element.This process is called "traversing the Node tree" Reading server-side XML (note the difference between different

JavaScript variable Scope detailed

JavaScript variable Scope detailed The scope of a variable is the region in the program that defines the variable. The scope of a variable is also called a scope, which refers to the valid range of a variable in the program. Depending on the scope,

JavaScript subString () method and slice () method

Web page Effects subString () method and slice () method The slice () method extracts a part of the string and returns the extracted part with a new string.GrammarStringobject.slice (Start,end)Parameter descriptionThe starting subscript of the

A method of judging the types of variables in JavaScript _javascript tips

In JavaScript, there are 5 basic data types and 1 complex data types, with basic data types: Undefined, Null, Boolean, number, and string; Complex data types are also subdivided into many specific types in object,object. For example: Array, Function,

JavaScript to determine if date format is correct implementation code _ time Date

The reprint is at least to indicate the author and the source! Http://www.cnblogs.com/GuominQiu Copy Code code as follows: //--------------------------------------------------------------------------- Determine if the date format is

The definition and way of classes in JavaScript (JavaScript Advanced Program Learning notes) _js Object oriented

The inheritance of classes in JavaScript can refer to Nanyi's blog, "The design idea of JavaScript inheritance mechanism", which is very well said. First, the problems encountered in JavaScript instantiation: Here's a description of the example in

"Repost" JavaScript event model event handling mechanism

What is an event?Event is the heart of the JavaScript app beating and the glue that sticks everything together. Events occur when we interact with certain types of Web pages in the browser. An event might be a user's click on something, a mouse

How to choose the right JavaScript framework in a program development project, save time and Cost 9 excellent JavaScript framework Introduction

technically , mobile apps on ios,Android and Windows Phone are developed in different programming languages, and iOS apps use Java with Objective-c,android apps, and The Windows Phone app Uses. NET. 。 With the improvement of JAVASCRIPT,CSS and HTML

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