javascript test if function exists

1. in prototype mode 1.1, each function we create has a prototype attribute, which is a pointer pointing to an object, the purpose of this object is to include attributes and methods that can be shared by all instances of a specific type. A simple

Directory1 History 2 clarifying misunderstandings 3 basic concepts 4 features 5 different from Java 6 development toolsHistoryProbably in 1992, a company called Nombas began developing an embedded scripting language called C-minus (C-minus-minus, or

Ask for a question. if the user name exists during registration, it will not be successfully registered. in this case, the user name can still be registered. Script $ (function () {// check whether the user name exists $ ("# name "). blur (function (

In many traditional languages (such as C/C ++/Java/C #), functions exist as second-class citizens, you can only declare a function with the keyword of the language and call it. If you need to pass the function as a parameter to another function, or

IntroductionIn many traditional languages (such as C/C ++/Java/C #), functions exist as second-class citizens. You can only declare a function with the keywords of the language and then call it, if you need to pass a function as a parameter to

Recently, due to work needs, I began to develop some Python things. because I have been using Javascript before, I will unconsciously use some Javascript Concepts, syntaxes, and so on. I think it is necessary to summarize the differences between

In the company's image server, the same product will generally have a corresponding large map and thumbnails. Therefore, when we develop the mobile Web site, the default is to use a thumbnail image of the product, to query the database is the path

A deep understanding of javascript function parameters and closures, and a deep understanding of javascript Recently I have been studying javascript Functions. functions are the first-class objects of javascript. To learn javascript well, I must

Compared with Javascript, Python has recently started to develop some Python things due to work needs. Since Javascript has been used for a long time, it will unconsciously use some Javascript Concepts, syntaxes, and so on, it often falls into a

Summary of little knowledge about JavaScript performance optimization, and javascript Performance Optimization With the development of the network, network speed and machine speed, more and more websites use a variety of client technologies. Ajax is