javascript complete reference

Reference types are important content in JavaScript. A reference type is a data structure that is used to organize data and functionality together. It describes the properties and methods of a class of objects. object is an underlying type, array is the type, date is the type, regexp is the regular expression type, and so on. Embrace

Memory leaksIn JavaScript, we seldom pay attention to memory management. We create variables, use variables, and browsers look at these underlying details as normal.But when the application becomes more complex and Ajax, or the user stays on a page for too long, we may need to pay attention to some problems, such as a browser that spends more than 1G of memory, and is constantly increasing. These problems are often caused by memory leaks.Javascript me

Reference | objects | Array useragent user and proxy header text sent by client to server Method javaenabled JavaScript does not currently have this method, but will soon add that it will see if the browser is compatible with JavaScript, and if so, continue to see if JavaScript is supported. b.22 Options Array The

"object definition" that is logically equivalent to a class in another programming language.A detailed explanation of JS objects is also available in the previous posting, for reference: Easy learning JavaScript nine: JavaScript objects and arrays.Let's take a look at an operator instanceof that determines a reference

type values, BL1 save a copy of the BL copy. The following illustration shows the process of assigning this basic data type: Look at the reference type data below: JavaScript reference data types are objects that are stored in heap memory and, unlike other languages, you cannot directly access the location in the heap memory space and the operating heap mem

Code Listing 1:var a=3.14;var b=a;a=4;alert (b);Code 2var a=[1,2,3];var b=a;a[0]=99;alert (b);Why does code 1 show 3.14, why does the value of a not change? Obviously, after executing the second line of code, we re-assigned a value. Is it because the value of the first row given to a is an underlying type that cannot be changed?That's why code 2 shows the value is 99,2,3, why the value of a is changed, because the array is a reference type, the

The ECMAScript variable may contain values for two different data types: the base type value and the reference type value. A primitive type value refers to a simple data segment, whereas a reference type value refers to an object that may consist of multiple values.When assigning a value to a variable, the parser must determine whether the value is a base type value or a

with an escape sequence. eval () computes the JavaScript code string, returning the result. The isfinite () verifies that a value is a number that is infinitely large. The isnan () verifies that a value is non-numeric. parsefloat () parses a number from a string. parseint () parses a number from a string. The unescape () decodes str

In JavaScript, the method often involves the context, that is, this, so often can not directly reference, take the most common console.log ("info ..."), avoid writing lengthy console, directly with the log ("info ...") instead, Think of the following syntax without hesitation:1 var log = console.log; 2 log ("info ...");Unfortunately, the operation error: Typeerror:illegal invocation.Why is it? For Console.l

Original link: 1190000006752076A variable can hold two types of values, the values of the base type (primitive values) and the value of the reference type (reference values).ES6 introduces a new primitive data type, Symbol, that represents a unique value. It is the seventh data type of the JavaScript language, the first six kinds are: Undefined, Null, Boolean (Bo

How to develop a complete JavaScript component (1) As a developer, you should know that there are some built-in controls in the browser: Alert, Confirm and so on, but these controls are usually different in form according to the browser manufacturer, visual effects often fall short of the requirements of UI designers. More importantly, it is difficult for these built-in controls to be consistent with the D

Javascript uses prototype to complete single inheritance, and jsprototype to inherit 1. Use prototype to complete single inheritance. Copy codeThe Code is as follows:// Define A ClassFunction (){}// For Class A dynamic call attribute color, and method sayColorA. prototype. color = "blue ";A. prototype. sayColor = function (){Alert (this. color );};// Creates a

The code is as follows: varHead = document.getElementsByTagName (' head ') [0]; varScript = document.createelement (' script '); Script.type= ' Text/javascript '; Script.charset= ' GBK '; Script.onload= Script.onreadystatechange =function() { if(! This. readyState | | This. readyState = = = "Loaded" | | This. readyState = = = "complete") {callback (); Script.onload= Script.onreadystatechan

Memory leaksIn JavaScript, we have very little attention to memory management.We create variables, use variables, and browsers look at these underlying details as normal.But when applications become more complex and Ajax-or users stay on a page for too long-we may need to pay attention to some issues. such as a browser to spend more than 1G of memory, and is constantly added.These problems are often caused by memory leaks.Javascript memory leaksThe co

This article mainly introduces the basic types and reference types of JavaScript data types. This article describes dynamic attributes, copy variable values, transfer parameters, and detection types, you can refer to the ECMAScript variable that contains two different data types: basic type value and reference type value. A basic type value is a simple data segme

The back-end management framework we applied to the project was basically the same, with a level two menu on the left, a click on the selected menu, and a corresponding page on the right. I put the front-end page encapsulation data process, although not necessarily suitable for all management pages, only as a case to reference, just hope you can understand the principle of implementation is good.　　The menu on the left is built:1, first, we need to app