javascript understanding weird parts

Know how to create objects using object literals ; (attributes are separated by commas ) Data Properties and accessor properties There are four characteristics of data attributes: writable, Configurable, Enumerable, Value Accessor properties have four attributes: Configurable, Enumerable, Get, Set Method: How to define multiple properties Method: How to modify property default attributes JavaScript Advanced Programming: Chapter 6th

1Retrieves the value of an object, which can be used to enclose a string expression (a valid identifier and not a reserved word). PointRecommended points, as this is more compact and readable.If a property that does not exist is retrieved, undefined is returned.2Attempting to retrieve values from undefined would throw a TypeError exception. ThisCan be guarded against with the operator:Flight.equipment//undefinedFlight.equipment.model//throw "TypeError"Flight.equipment Flight.equipment.model//u

Extract A good parts of a language or technology and use this subset to construct robust and stable applications. We are always inclined to learn and use all the language features, as if all new and provided are necessary to use them. This book tells us that we should learn and use them selectively. Not all language features need to be learned and used. Learning and using poorly designed features not only consumes a lot of time and energy, but also d

A deep understanding of the scope of this in Javascript and a deep understanding of javascript This guy often gets dizzy when using Javascript. For most developers with OOP development experience, this is the identifier that references common elements in the current scope, b

A deep understanding of the synchronous and asynchronous mechanisms in JavaScript programming and a deep understanding of javascript One of the advantages of JavaScript is how it handles asynchronous code. Asynchronous code will be put into an event queue and will not block

A deep understanding of javascript variable declaration and a deep understanding of javascript Compared with C/C ++, The for loop in ECMAScript cannot create a local context. Copy codeThe Code is as follows:For (var k in {a: 1, B: 2 }){Alert (k );} Alert (k); // although the loop has ended, the variable k is still in t

A deep understanding of the JavaScript series (27): The Builder mode of design patterns, and a deep understanding of javascriptIntroduction In a software system, sometimes it is faced with the creation of "a complex object", which is usually composed of sub-objects of each part using a certain algorithm; due to changes in requirements, the various

The following things are not what I have created. They are the essence of some books I think. After learning about JavaScript, I feel that my understanding of JavaScript has been further improved, find out something that is also known as a trick or a trick. I will apply this knowledge to a new framework. The goal of the new framework is to use js to display vario

= '# f00 ';}// Initialize and register events for all a tagsFunction init (){Var customLinks = document. getElementsByTagName ('A ');For (I in customLinks ){// You can also use the event listener to register events// To be compatible with IE, FF, and other browsers, you may need more code.CustomLinks [I]. onclick = changeColor;}}Window. onload = init; Add this code to the HTML document and add some hyperlinks to the document. When the hyperlink is clicked, the color turns red. Here we define c

global variable is declared as follows:"Variable name"inchwindow Second, all the variable declarations are at the top of the range scope and look at similar examples: alert (Ainchwindow);varA; At this point, although the declaration is after alert, the alert pop-up is still true because the JavaScript engine first graves all the variable declarations and then moves the variable declarations to the top, and the final code effect is this:varA;alert (Ai

In the previous article, I ended the creation of objects and finally introduced the issue of scope chain and execution environment. When I have a deeper understanding of this knowledge, I will look back at the jQuery source code to know how powerful the code written by masters is, the jQuery source code uses the scope chain and execution environment knowledge to improve program performance. Okay, no nonsense. The scope mentioned in the previous blog i

In the previous article, I ended the creation of objects and finally introduced the issue of scope chain and execution environment. When I have a deeper understanding of this knowledge, I will look back at the jQuery source code to know how powerful the code written by masters is, the scope chain and execution are well applied in jQuery source code... syntaxHighlighter. all (); In the previous article, I ended the creation of objects and finally intr

'; Skills is in the local scope because of the ' const ' keyword const skills = ' JavaScript and PHP ';} console.log (name) ; Logs ' Hammad ' Console.log (likes); Uncaught Referenceerror:likes is not definedconsole.log (skills); Uncaught Referenceerror:skills is not defined　　The lifetime of a global scope in an app is the same as the application. A local scope exists only during the execution of the function call.ContextMany developers often co

DescriptionThis tutorial bypassed some basic JavaScript syntax, directly explaining the two most difficult parts of JavaScript, and the two most significant differences from other mainstream object-oriented languages- prototypes and closures, and of course, the prototype chain and the scope chain. Help you uncover the most mysterious veil of

DescriptionThis tutorial bypassed some basic JavaScript syntax, directly explaining the two most difficult parts of JavaScript, and the two most significant differences from other mainstream object-oriented languages- prototypes and closures, and of course, the prototype chain and the scope chain. Help you uncover the most mysterious veil of

This article mainly introduces the new understanding of this pointer in JavaScript. this article describes the method call mode, function call mode, constructor call mode, and the understanding of this pointer in the Apply call mode, if you need this, you can refer to the previous understanding of this. This time, I ma

, the second Console.log statement would run before the first, because the callback ' t executed until the request Is over, and until this happens the rest of the code goes right on ahead and keeps running.Wrapping it UpHopefully now-should understand callbacks well enough-use them in your own code. I still find it hard-structure code that's based around callbacks (it ends up looking like spaghetti ... my mind is too a Ccustomed to regular structured programming), but they ' re a very powerful t

be different.The alert in the "foo" function has not changed.But this is different every time the call is activated.function foo () { alert (this);}Caller activates the callee "foo",and provide "This" to this calleeFoo (); Global objectsFoo.prototype.constructor (); Foo.prototypevar bar = { Baz:foo};Bar.baz (); Bar(Bar.baz) (); Also bar(Bar.baz = Bar.baz) (); This is a global object(Bar.baz, Bar.baz) (); is also a global object(False | | bar.baz) (); is also a global objectvar otherfoo = Bar.

This tutorial bypassed some basic JavaScript syntax, directly explaining the two most difficult parts of JavaScript, and the two most significant differences from other mainstream object-oriented languages-prototypes and closures, and of course, the prototype chain and the scope chain. Help you uncover the most mysterious veil of JavaScript.Why do we have to talk

This article mainly introduces the new understanding of this pointer in JavaScript. this article describes the method call mode, function call mode, constructor call mode, and the understanding of this pointer in the Apply call mode, if you need this, you can refer to the previous understanding of this. This time, I ma