null or undefined

Data typeJS has a total of six data types, including five basic data types, number, String, Boolean, Null, Undefined, and a complex data type--object type.typeofThe typeof operator detects the data type of a given variable, and returns a function,

Recently reading an advanced JavaScript book, "You Don't know the JavaScript (roll up)", this time study "this".When a function is called, an activity record ( execution context ) is created.This record contains information about where the function

Recently in the bad to fill JS knowledge, always will because of JS strong grammar and feel shocked. Because the previous neglect of the front end, led to some understanding of the error. So repent, make up your mind, no matter what you do, have the

introduce yesterday's "Uncle's Notes" (19): Do you really understand JavaScript? "Inside of the 5 topics, there are many answers, found that the strongman or a lot of people are all correct." Today, we will analyze these 5 topics in detail and hope

Utility functions, the $ namespace for a series of functions, but does not manipulate the wrapper set. It either operates on JavaScript objects other than DOM elements, or performs some non-object-related operations. Browser detection flags for

xCatalog [1] query [2] settings [3] Delete [4] inherit the preceding wordsFor an object, property manipulation is a topic that cannot be bypassed. Similar to the basic operation of "Delete and delete", attribute operations are divided into attribute

Chapter 4 StatementFormally, a statement is a piece of code that ends with a semicolon. Whether this code is an expression, something else, or even nothing, as long as it ends with a semicolon, it can be considered a statement.Functionally, a

Learning notes for call and apply in Javascript, and learning notes for apply First, let's look at the call explanation in MDN. The call () method calls a function or method when a specified this value and several specified parameter values are used.

File System FSThe FS module is the encapsulation of file operations, which provides file read, write, rename, delete, traverse directory, link and other POSIX (note: Portable Operating System Interface: Portable Operating system Interface,

JQuery. parseJSON (json) converts a JSON string to a js object, and the jquery string to json Overview Accepts a JSON string and returns the parsed object. Inputting a malformed JSON string throws an exception. For example, the following are

Determination of variable types in javascript   In JavaScript, there are 5 basic data types and 1 complex data type. The basic data types include:Undefined,Null,Boolean,NumberAndString; The complex data type isObject,ObjectIt also subdivided into

In a word: = convert the type before comparison, = first judge the type, if not the same type, it is directly false.===Indicates constant equals, and the two sides of the comparison must be absolutely the same alert(0 == ""); // truealert(0 == false)

For details about the extend () and fn. extend () methods in jQuery, jqueryfn. extend The two methods use the same code. One is used to merge attributes and methods for jQuery objects or common objects. The other is an example of jQuery objects. for

Chapter5 Reference typeThe contents of this chapter:L Use objectsL Create and manipulate arraysL understand basic JavaScript typesL use basic type and basic packing typeTechnically, JavaScript is an object-oriented language, but it does not have the

JS in the 6 major types: Number,string,boolean,null,undefined,object, where null and undefined accounted for 2 seats, and their role is to represent the empty, In my usual work I have not found the difference between the two, then what is the

The operator priority in JavaScript is a set of rules. This rule controls the order in which operators are executed when calculating expressions. Operators with higher priority are executed before operators with lower priority. For example,

C # overview of various operators and functions of operators,I. [] Square brackets ([]) are used for arrays, indexers, and attributes, and can also be used for pointers. 1. the array type is a type followed: Int [] fib = new int [100]; // create an

Jquery.extend is one of the most important ways of jquery, so let's look at how jquery can be implemented to extend operations1 //If an object is passed in, the object's properties are added to the jquery object2 3 //if two or more objects are

JS data type conversion method mainly has three kinds ofConversion function, coercion type conversion, using JS variable weak type conversion.1. Conversion function:JS provides two conversion functions for parseint () and parsefloat (). The former

ECMAScript can recognize two types of objects: Native Object and Host Object, which are provided by the runtime environment, for example, document Object,Dom NodeNative objects is a loose structure and can dynamically add properties. All attributes