JavaScript scope and scope chain for a simple introduction

JavaScript scopes Any programming language has the concept of scope, in short, the scope is the accessibility of variables and functions, that is, the scope controls the visibility and life cycle of variables and functions. In JavaScript,

JavaScript color gradients and gradient effects

Tip: You can modify some of the code before running JavaScript color gradients and gradient effects javascript color gradient and gradient effect Color Gradient Demo: simple color picker: Select color: Color

JavaScript get picture Width High Example Summary

A simple way to get pictures The code is as follows Copy Code The time stamp behind the picture address is to avoid cachingvar img_url = '/static/upload/2013/13643608813441.jpg? ' +date.parse (New Date ());Creating

JavaScript constructors are automatically executed using the New keyword

JavaScript is a lightweight and imprecise programming language with basic syntax, but although lightweight and simple, but sometimes it can get you, this is an interesting article, perhaps you have written a JavaScript function or the use of

JavaScript Data Capacity Unit conversion (KB,MB,GB,TB)

For example, when we refer to "data transfer speed" and "hard disk storage space", kilobytes represent 1000 (103), and when it comes to memory or CPU cache capacity, kilobytes represent 1024 (210) because they are stored here by byte-code address.

new function () Considerations in JavaScript

The code is as follows Copy Code Varyx01=new function () {Return "center"};alert (yx01);//[objectobject] Equivalent: The code is as follows Copy Code function Anonymous class () {return "center";

Number of occurrences of each character in the JavaScript calculation string

  code is as follows copy code function CharCount (str) {Replaces characters from a string with a regular match, using match () with a regular match. Length gets the number of occurrences of each characterstr = str.replace (/s/ig,

JavaScript Object-Oriented inheritance notes

Yes, we have to understand the inheritance model first to understand the prototype chain of this thing.One: Prototype chainThe basic idea is to have a reference type inherit the properties and methods of another reference type. To understand the

Learning notes for the scope of JavaScript

Preface: Before read a saying, if cannot take the knowledge to a person to parse clearly, the explanation actually also did not understand. The code is as follows Copy Code The first three paragraphs describe the scope of

Javascript Bitwise counter Operator some detailed

Performs a bitwise non-(negation) operation on an expression. result = ~ Expression Parameters ResultAny variable. Expression Any expression. Note All unary operators, such as the ~ operator, calculate the value of an expression according

Javascript Form Validation instance code before submitting


Cases Add the onsubmit attribute to the form or the Add OnClick property of the Submit button, the value is return check (), the check is a JavaScript function, the validation table is single, no call, even if the validation fails will be submitted.

JavaScript Date Format Function performance comparison

Log functionality is needed in recently developed software, and one of the important features is the display of dates and times. So a search on the Internet, search to a large number of date format functions, but compared to the next, the sense of

Encyclopedia of string manipulation functions in JavaScript (including regular)

*******************************************JS Self-band function*******************************************/ ConcatCombines the text of two or more characters to return a new string.var a = "Hello";var B = ", World";var C = A.concat (b);alert (c);c

JavaScript string Operations Summary of some methods

Isfinite (123);//detection is a number (this returns TRUE)isNaN (123);//detection is not a number (return false here) ' Hello World '. IndexOf (' A ', 2);//Find matching character position does not return-1, note the following optional parameters

JavaScript new Function (") and new function () {} instance

Scenario One: The code is as follows Copy Code var yx01 = new function () {return "center"};alert (YX01); We run the story one code, and it returns "[Object Object]", which is equivalent to: The

JavaScript Boolean () and if learning notes

More recent interviews, but every time I asked this question, the answer came out of the students are not many The code is as follows Copy Code var a = 0; if (a) { alert (

JavaScript test, search, replace, split regular usage

Match methodPerforms a lookup on a string using the regular expression pattern and returns the result that contains the lookup as an array.Stringobj.match (RGEXP)ParametersStringobjRequired option. A string object or string literal to find

JavaScript If Else Description

if (condition){Execute code when conditions are set}--> if (condition){Execute this code when the condition is set}Else{Execute this code when the condition is not true} You can use the If....else statement if you want to execute a piece of

JavaScript cookies Save, get and delete instances

function Setcookie (name, value)//cookies set JS{var argv = setcookie.arguments;var argc = setCookie.arguments.length;var expires = (argc > 2)? ARGV[2]: null;if (expires!=null){var largeexpdate = new Date ();Largeexpdate.settime

Whether a variable in JavaScript is a value or a pass

But it is the key to understanding data structures. The 4 terms in the title, corresponding in English are: shallow copy (note, not shadow copy), deep copy, pass by value, pass by reference (or pass by address). It's one thing to pass and pass

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