null or undefined

JS integer, float type converted to complex type JS data type conversionThere are three main methods Conversion functions, forced type conversion, and weak type conversion using js variables. 1. conversion functions: Js provides two conversion

Introduction to packaging types in Javascript and javascript packaging types Recently, I did not read the rhino book. The translation was very bad and easy to understand, especially the prototype. Later I was introduced by my colleagues and I bought

Summary of Javascript Array In several reference types of JavaScript (Object, Array, Date, RegExp, Function, basic reference type), the Array type should be the most applied type except for the object. Unlike other languages, arrays in ECMAscript

Implicit JavaScript conversions and implicit javascript Conversions The JavaScript data type is very weak (otherwise it will not be called a weak type language )! When Arithmetic Operators are used, the Data Types on both sides of the operators can

Call apply and bind methods in javascript, applybind In JavaScript, call, apply, and bind are the three methods that come with the Function object. In this article, three methods are described in detail through the application of several

JavaScript compares two methods for equality. javascript is equal. This article describes how JavaScript compares two objects. Share it with you for your reference. The details are as follows: In Python, you can use the cmp () built-in function to

Introduction to Strict Mode in ECMAScript 5 This article mainly introduces the Strict Mode of ECMAScript 5. This article describes how to enable the Strict Mode and how it affects variables, attributes, functions, and with statements after the

In-depth understanding of Object Clone and javascriptclone in JavaScript JavaScript does not directly provide the Object Clone method. Therefore, when object B is changed in the following code, object a is changed. A = {k1: 1, k2: 2, k3: 3 }; B =; B.

Bash condition test-empty string confusions: bash condition string You can use-n or-z to check whether a string is null. According to the meaning of the operator, if VAR is null or undefined, the-n test result should be false, and-z should be true.

Javascript system, Array object learning notes, array learning notes An array is a set of values in order. The attribute names of objects are unordered. In essence, arrays use numbers as search keys, and objects have custom attribute names.

I. Expressions 1. The JS interpreter can calculate it to generate a value; 2. The simplest expression is the direct amount or variable name. The value of the direct amount expression is the direct amount; 123; "I am a string" I + 1.7; (a + 3) *

A friend recommended book (http://eloquentjavascript.net/), while not busy recently read the next. In general, this book is not suitable for beginners of JS, because the examples in it are relatively poor, less academic, and practical applications.

ArticleDirectory Overview Parameters Example Overview Accepts a JSON string and returns the parsed object. Inputting a malformed JSON string throws an exception. For example, the following are malformed JSON strings: {Test: 1} (test

Distinguish underfined, null, and Nan First, let's look at the running result of the following statement: 1: VaRA; 2:Alert ();// Display "undefined" 3:Alert (TypeofA );// Display "undefined" 4:Alert (B); // display"Undefined" The value

The three main primitive values, Boolean values, numbers, and strings, all have the tostring () method. Tostring can also contain a parameter, that is, its base mode.The base mode of the tostring () method of the number type can be used to output

Getelementsbyclassname () To read a large number of HTML Code To find out the tree menu (maybe there are multiple), let's first implement a method to find the DOM node through classname: getelementsbyclassname. This is a simple but practical

It seems that I have also seen null = undefined, null! = Undefined. One of the pastProgramSource code, such as if (X! = Undefined & X! = NULL & X! = "") And so on, suddenly felt that the write is very wordy, I usually directly if (X) {} No matter

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

There are three main methods for js to convert strings to numeric values. Conversion functions, forced type conversion, and weak type conversion using JS variables. 1. conversion functions: JS provides two conversion functions: parseint () and

There are three main methods Conversion functions, forced type conversion, and weak type conversion using JS variables. 1. conversion functions JS provides two conversion functions: parseint () and parsefloat. The former converts the value to an