JavaScript Math Object

Math.PI This value is approximately 3.141592653589793.Math.ceil (x) rounding upMath.floor (x) rounding downMath.pow (x, y) returns the Y power of X (Note: If the result is an imaginary or negative number, the method returns NaN.) If a floating-point

JavaScript Learning Second Lesson--① input judging ② provinces and cities linkage

Try to set reminders, catch to capture return values② Provinces and cities linkageTo fill the loop before emptying,The code is as follows:DocumentCountry: City: Location: JavaScript Learning Second Lesson--① input judging ② provinces and cities

JavaScript QuickStart-ecmascript Local objects (Array)

Array ObjectThe array object, like the list object inside Python, is an object that stores multiple object values, and the methods and properties are basically similar.First, the attributeLenghtSecond, the method1, concat () is used to connect two

JSON (JavaScript Object Notation)

What is JSON:is a data interchange format that can replace XML    JSON syntax rules:in the JS language, everything is an object. Therefore, any supported type can be represented by JSON, such as strings, numbers, objects, arrays, and so on. However,

JavaScript: Regular expressions, an example of a form validation

Read Catalogue The content of this article: Regular Expressions: Examples of forms validation using regular expressions: Back to top of this article: Regular expressions How to use regular expressions

The difference between substring (), substr (), slice () in JavaScript

1.stringobject.substring (start,stop) is used to extract the character of a string intermediary between two specified subscripts.(1) Start required. A nonnegative integer that specifies the position of the first character of the substring to be

variables, data types, operators, process structures for "Rough Edition" javascript

The content of this article: Variables for JavaScript Data types for JavaScript The JavaScript operator The process structure of JavaScript Starting Date: 2018-05-09 Variables for JavaScriptTo create a variable:Global

Getting Started with JavaScript

Read Catalogue (Original-moe little Q) One, you know, why is JavaScript so worthwhile for us to learn? Second, easy to learn sex Three, where to start learning? Iv. How to insert JS V. Quoting JS external file Six, JS in

JavaScript basics from shallow into deep understanding (i)

Introduction to JavaScriptJavaScript is a dynamic, weakly-typed, interpreted programming language that enhances page dynamics and enables real-time dynamic interaction between pages and users.JavaScript is made up of three parts: ECMAScript, DOM,

The difference between = = and = = in Javascript

"= = =" is called the strict operator, and "= =" is called the equality operator.The operation rules for strict operators are as follows,(1) Different types of valuesIf the two values are of different types, return false directly.(2) Primitive type

JavaScript array knowledge case of the random name register

The main points of this sharing JavaScript are the use of a For loop, an if selection structure judgment statement, an array definition, a timer, a purge timer, and a Date object.after execution:Ideas:1. Web structure: HTML2. Web Page layout: CSS3.

JavaScript arguments, parameters, and variables

(1) What is the difference between what is a formal parameter in a JS function and what is an argument? Parameters are called parameter variables, and the variables received by the function in JS are divided into formal parameters and arguments. An

JavaScript for the front-end base

JavaScript Overview of JavaScript history 1992 Nombas developed the embedded scripting language for C-minus-minus (c--), which was originally bound to Cenvi software, and renamed it Scriptease (the language that the client executes).

JS Tutorial Series 10:javascript switch statement

1 Switch statements are useful:The switch statement is used to perform different actions based on different conditions.Whenever a variable condition is met, the current case content is executed. The break keyword is used to jump out of a switch code

This is the JavaScript learning

Transferred from: 1:function A () { var user = "Chasing the Dream"; Console.log (This.user); Undefined console.log (this);//window}a ();As we said above, this finally points to the object

JavaScript self-increment, decrement operator

JavaScript self-increment, decrement operator, and expression syntaxvari++; var--Declaring variables i--Variable name ++--Self-increment operator JavaScript self-increment, decrement operator and expression JavaScript

JavaScript learning log (1)

JavaScript usage:1, the script in the HTML must be between tags, can be placed in the HTML page and section;2, you can also put the script in the external. js file, you need to use, in the HTML section: After running the original HTML page is

JavaScript Advanced Programming Learning Note 2

Garbage Collection principle:Identify the variables that are no longer in use, and then release their memory.The most commonly used garbage collection method in JS is tag cleanup , when variables enter the environment, the variables are marked as "

Array objects in JavaScript

1. Three ways to create an array: 1.1 var array name =[element 1, Element 2, Element 3 ...];For example:var arr1=[1,2,3,4];1.2 var array name =new Array (element 1, Element 2, Element 3 ...)For example:var arr2=new Array (5,6,7,8);1.3 Assigned to an

Analysis of JavaScript Design Patterns-publish-subscribe/Viewer mode

I've been writing CSS3 articles for some time.I've never written design patterns.To write about the famous observer pattern today.Draw a picture firstUnderstanding of the Observer patternI think it's easier to say that the publish-subscribe model is

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