object undefined

Multidimensional array to one-dimensional array: [1,[2,3]] = = [[+]]function Tran (array) { if (Object.prototype.toString.call (array)! = ' [Object array] ') { alert ( Object.prototype.toString.call (Array) + "non-array" ) return

1. Data typeJavaScript has a total of six data types. (ES6 added a value for the seventh symbol type) Value (number) Strings (String) Boolean Value (Boolean) Undefined Null Objects (object) 2. Data type

　　1, typeof Supports basic types of acquisition, such as Boolean, string, number, function, object, undefined 　　Usage: var v = true;//"string", typeof V; Boolean Ps:array/date/null are object,undefined for undefined. 　　2, instanceof When you

1, typeof (Param) Returns the type of Param (string) This method is the definition of JS in the global approach, but also compilers are the most commonly used method, the advantage is that the use of simple, good memory, the disadvantage is not

In JavaScript, the most reliable way to determine what kind of built-in type an object's value belongs to is through the Object.prototype.toString method. var arr = []; Console.log (Object.prototype.toString.call (arr))//"[Object Array]"

background : Most browsers have implemented the native API support for JSON object-turn strings, so how do you do that in a lower browser browser, such as your favorite ie6--?First, run the following methods to test the output of json.stringify in

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,

Several data types of JS: Number, String, Boolean, object, undefined five types of data Common built-in object classes for JS: Date, Array, Math,number,boolean, String, RegExp, Function,object. Two types of JS methods to judge: typeof,

When discussing the primitive data types in JavaScript, most people know the basic knowledge, from String, Number to Boolean. These primitive types are quite simple and behavior is common sense. However, this article will focus more on the unique

Background: Most browsers have implemented native api support for converting json objects to strings. How can this be achieved in earlier browser versions, such as Internet Explorer 6, which is your favorite?First, run the following method to test

Introduction　　JavaScript is a very strange language to use in some situations. This article will try to gather together some of the more special usages of this language. It is a place to be aware of when developing at ordinary times.Special Usage

JavaScript is a weak type or dynamic language. This means that you do not need to declare the variable type in advance. During the program running, the type will be automatically determined. This also means that you can use the same variable to save

JavaScript is a weak type , or dynamic language. This means that you do not have to declare the type of the variable in advance, and the type is automatically determined during the program's run. This also means that you can use the same variable to

DescriptionIntroducing JavaScript data typesDirectory Objective Reference sources Front-facing technical requirements 6 Types of data for JavaScript What 6 types of data Undefined type Null

Before I start, I want to throw a question, = = and = = What is the difference? Probably the average person will think, is not the latter in addition to comparing the value of equality will also compare the type is equal, what is good to ask, who do

Why is the type judgment used Object.prototype.toString.call () for type judgment , without typeof ()? And then flipping through the information:TypeofWhen usingtypeofOperator is a problem when storing values with reference types, regardless of what

Nonsense: Originally, this prototype source code analysis was intended only for taking notes on Prototype Learning. However, sometimes a problem can be found to be more in-depth (although it is still an analysis), which breaks away from the original

Judgment of variable types in javascript, javascript Variables Address: http://www.xiabingbao.com/javascript/2015/07/04/javascript-type In JavaScript, there are 5 basic data types and 1 complex data type. The basic data types include:Undefined,Null,

Detailed description of javascript deep copy (deepClone), javadeepclone Javascript deep copy is a problem that can be frequently encountered by beginners and even experienced developers. It is not easy to understand the deep copy of javascript. Deep

A tour of Javascript Data Types Although Javascript is a weak type language, it also has several data types, including Number, String, Boolean, Object, Udefined, and Null. Objects are complex data types, and they are composed of unordered key-value